subject:"RE\: Reminder\: Never connect a generator to home wiring without transfer switch"

> On Aug 31, 2021, at 09:23 , Sabri Berisha  wrote:
> 
> - On Aug 31, 2021, at 2:11 AM, Forrest Christian (List Account) 
> li...@packetflux.com wrote:
> 
> Hi,
> 
>> I just wish the electrical code would permit or require certain low cost 
>> things
>> which make temporary generator connections more likely to be safe.
> 
>> For example, code requires most furnaces to be hardwired. But a furnace is 
>> one
>> of the first things you want on a generator in an extended winter power 
>> outage.
>> If instead of hardwired, the code required plug and socket connections at 
>> each
>> 120v furnace then Joe homeowner would be more likely to run an extension cord
>> from his generator to his furnace instead of trying to rig up his generator
>> with a suicide cord.
> 
> Now I'm wondering which jurisdiction you're talking about. I live in 
> California
> in a home which was finalized in 2019. As I'm the first owner, I was there 
> when
> the inspector went up into the attic and checked my HVAC. My HVAC has a plug 
> in
> power cord running into a regular household socket (all in the attic). The 
> inspector didn't say a word about it and issued the occupancy permit.
> 
> My electrically powered oven is hardwired, but I guess that's because it 
> requires
> two 50amp breakers?

It only sort of looks like two 50amp breakers… In reality, it’s a “ganged” 
breaker that is
50A on both sides of a 220V circuit so that if either side of the circuit 
exceeds 50A,
it will trip both breakers and shut down both sides.

A 220V circuit in the US (or 215/230/240, varies widely from utility to utility 
and for
other reasons) is both hot sides. The three wires coming into your house from 
the
utility are the two hots from opposite ends of the secondary winding in the 
utility
stepdown transformer along with a center-tapped “neutral”. The neutral is (or 
at least should be) tied to earth ground at exactly one place in your home 
(usually
inside the main breaker panel). The two “hot” sides each provide a 
110V(approximately)
AC source relative to the reference (0V Neutral and Ground), but they provide 
that
at a phase difference of 180º. This means that the potential between the two
hot lines is (nominally) 220VAC.

Owen

Re: Reminder: Never connect a generator to home wiring without transfer switch

Here’s an example of the type I was describing in my previous post:

https://diy.stackexchange.com/questions/23330/how-can-i-retrofit-this-existing-wall-heater-with-an-external-thermostat

(Primarily for the image, not the subject matter of the page)

Re: Reminder: Never connect a generator to home wiring without transfer switch

> On Aug 31, 2021, at 07:41 , Mel Beckman  wrote:
> 
> Mark,
> 
> But you said “Gas-fired furnaces or heaters should not have an impact because 
> the only electrical requirement is to fire up the pilot light.” There is no 
> gas-fired furnace I know of that doesn’t require a blower fan. How else does 
> the heat get out of the furnace?

For central heating, you’re absolutely correct. However, there used to be 
(don’t know if they are still sold in the US) wall-mounted single and/or 
double-sided gas radiant heaters that distributed hot air out of the top via 
convection and radiated heat from a vertical heat exchanger as well.

> To answer your question, you need to understand that this safety system has 
> two components. The first component, the furnace interlock relay, is designed 
> to interlock the blower with the forced-air system, which also includes an 
> outside air supply valve. When the blower is energized, a circuit inside the 
> furnace gets power. The blower and furnace operate continuously when this 
> circuit is energized, and the supply valve opens and closes as needed to 
> ensure the air doesn’t get stale.

I have no such valve (external air) in my house. I suspect this is applicable 
primarily in industrial/commercial HVAC.

The blower interlock is also slightly different in how it operates on my system.

When the thermostat calls for heat, the electronic ignition starts up. When it 
reaches ignition temperature, the gas solenoid is activated and the burner 
lights off. If ignition is not detected within a set period of time, the 
safeties will shut the system down to error mode.
Assuming ignition is detected, the blower is engaged. If the blower fails to 
start or the temperature in the flame box exceeds a certain value, then the 
safeties will shut the system down to error mode.

> The safety second component is the limit switch, which primarily turns the 
> blower fan on and off, but also has a safety role. When the temperature in 
> the air supply plenum gets too hot, the limit switch turns off the furnace 
> burner (or boiler, in a water-based system) to prevent damage, and possibly a 
> fire, from overheating.
> 
> The actual state mechanics are thus not as simple as “if the blower fails the 
> furnace won’t light”. And it’s because of these complex state mechanics that 
> furnace electricity is hard wired.
> 
> Without AC power, no furnace can operate in a power outage. So that’s 
> certainly not “no impact” from a utility failure. But the many thousands of 
> deaths that occurred in homes and offices before these safety systems were 
> put into the code is why you need a generator transfer switch if you want 
> heat (or A/C) in your home during an outage.

Yep… Unless you have an old-fashioned fireplace, in which case, you can have 
heat without electricity.

Owen

Re: Reminder: Never connect a generator to home wiring without transfer switch

> On Aug 31, 2021, at 07:15 , Mark Tinka  wrote:
> 
> 
> 
> On 8/31/21 16:06, Mel Beckman wrote:
> 
>> I think you’re forgetting about the all-important blower fan in a gas-fired 
>> furnace.
> 
> Well, I was referring to a pure electric furnace, not one that uses a blower 
> over a gas-fired one :-).
> 
> In that case, the blower is not a major draw on power.
> 
> But again, we don't have those things here, so :-).
> 
> 
>> That said, the reason the code requires furnaces to be hardwired is to 
>> ensure that the blower interlock system can’t be bypassed. An electrical 
>> interlock ties a heat recover ventilator to circulation air blower operation 
>> of a forced-air furnace system. This ensure that the blower circulates 
>> supply and return air within the structure. A plug-in power source leads to 
>> the possibility that this interlock could be accidentally defeated, 
>> resulting in an overheat within the flame box.
> 
> Makes sense.
> 
> Does this, then, mean that if the blower itself were to fail, the gas burner 
> would not light?

Yes… Sort of.

In most cases, the burner lights off ever so slightly before the blower starts 
up (if you’ve ever tried to light a campfire in high wind, you’ll understand 
why).

However, if the blower fails to start producing wind on demand, the gas to the 
burner will be shutoff and the system will go into an error mode requiring a 
reboot or service intervention.

Of course a reboot without correcting the blower issue probably results in a 
repeat of the process.

Owen

Re: Reminder: Never connect a generator to home wiring without transfer switch

> On Aug 31, 2021, at 03:36 , Mark Tinka  wrote:
> 
> 
> 
> On 8/31/21 12:26, Forrest Christian (List Account) wrote:
> 
>> Yes.   Or any other furnace where the electricity is only used for 
>> circulation of the heat.  Gas fired Hot water furnaces would be another 
>> example where there is minimal electricity used to run the furnace controls 
>> and circulate the hot water.
> 
> Gas-fired furnaces or heaters should not have an impact because the only 
> electrical requirement is to fire up the pilot light.

Depends… Forced air gas-fired furnaces (as in most central heating systems) 
also need something to run the squirrel-cage blower.

Most gas furnaces that are not forced air these days do require some 
electricity to run the thermostat, but that’s usually generated from the pilot 
light (very low current 24VAC for the “C” wire).

Don’t get me started on the whole mess that is the C-Wire and the various hacks 
to accommodate legacy systems that don’t have one.

> But fully-electric heating has a much higher impact on energy sources (heat 
> pumps being the least).

Yep.

> I believe typical electric central furnaces are anywhere between 10kW - 15kW 
> systems. Would a standard 4kVA - 8kVA generator for average Jane cut it? Not 
> sure.

15kW is 1.5kVA in a simple radiant electric heat application. (it’s a simple 
resistive load with no power factor weirdness). Whether you could do this with 
4-8kVA depends on what else you’re trying to run.

If you’ve got 3 teenagers all trying to run blow-driers at the same time and 
you also want to run your electric clothes dryer, you’re probably SOL.

If you’re trying to charge a cellphone, a laptop, and run a mostly closed 
refrigerator/freezer, you’re probably OK.

> Then again, I live in a more forgiving climate, so I have a very limited need 
> to understand this better.

Louisiana actually mostly doesn’t get all that cold. In fact, AC is a more 
likely issue in Louisiana than heating.
In the winter, Tennessee gets down to ~9.4C on average (49F), which is still 
well within human tolerance with blankets/coats/sleeping bags.
This time of year, it still tends to be fairly warm there, similar to Louisiana 
(in fact, today’s temperatures in both states are nearly identical).

> But I can understand why the code has not caught up to this yet, and insists 
> on hard-wiring the devices... because the majority of home and buildings will 
> still be using all-electric equipment that require plenty of energy, where 
> things can go wrong if you allow Jane to just run her suicide cord any way 
> she may like. Yes, there may be more folk moving over to other energy sources 
> that eliminate or reduce the need for electricity, but the code has to cater 
> for the wider demographic.

There are a multitude of reasons that a suicide cord is a bad idea beyond just 
the load planning issues and the lack of understanding
of load planning by the average consumer. The average consumer probably doesn’t 
understand that it’s a bad idea to feed 100A
of current through a “heavy duty” 20A extension cord into a 15A outlet to 
back-feed 200A panel through a 15A breaker.

Owen

Re: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-31 Thread Jay Hennigan


On 8/31/21 07:06, Mel Beckman wrote:

Mark,

I think you’re forgetting about the all-important blower fan in a gas-fired 
furnace.


We're *really* getting in the weeds here. A single note to the list 
about not backfeeding has really blown up.



That said, the reason the code requires furnaces to be hardwired is to ensure 
that the blower interlock system can’t be bypassed. An electrical interlock 
ties a heat recover ventilator to circulation air blower operation of a 
forced-air furnace system. This ensure that the blower circulates supply and 
return air within the structure. A plug-in power source leads to the 
possibility that this interlock could be accidentally defeated, resulting in an 
overheat within the flame box.


This doesn't compute. In a conventional forced air furnace the 24V 
transformer operating the thermostat, logic, and gas valve is powered by 
the same electrical source as the blower. In the event of someone 
unplugging the furnace, or for that matter a power failure, the gas 
valve will close when the power disappears.


Yes, there are old-school pilot light thermocouple-powered gas valves in 
wall and floor heaters that require no electricity at all. They rely on 
convection to distribute the heat, not a blower.


--
Jay Hennigan - j...@west.net
Network Engineering - CCIE #7880
503 897-8550 - WB6RDV

Re: Reminder: Never connect a generator to home wiring without transfer switch





On 8/31/21 18:32, Jay Hennigan wrote:



More likely a forced-air gas furnace with an electric blower. An 
electric furnace would be a heavy lift for a portable generator.


Yes, this was my thinking, until Mel clarified.

Mark.

Re: Reminder: Never connect a generator to home wiring without transfer switch




On 8/31/21 17:07, Warren Kumari wrote:




Depending on what you mean by furnace -- in some places, the term is 
used to cover basically any permanent (usually non-wood) heater. We 
have something like this in a holiday/weekend property: 
https://www.vermontcastings.com/products/radiance-direct-vent-gas-stove?page=Options 



Pretty much all the furnaces I've seen in southern Africa are 
wood-fired, with a vent that trails up into the ceiling, or comes out of 
the house as a chimney.


The heat is radiated either via the vent or directly from the front 
access, or both.


Mark.

Re: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-31 Thread Jay Hennigan


On 8/31/21 02:19, Mark Tinka wrote:



On 8/31/21 11:11, Forrest Christian (List Account) wrote:


For example, code requires most furnaces to be hardwired.  But a 
furnace is one of the first things you want on a generator in an 
extended winter power outage.   If instead of hardwired, the code 
required plug and socket connections at each 120v furnace  then Joe 
homeowner would be more likely to run an extension cord from his 
generator to his furnace instead of trying to rig up his generator 
with a suicide cord.


Are you referring to a forced-air central electric furnace?


More likely a forced-air gas furnace with an electric blower. An 
electric furnace would be a heavy lift for a portable generator.


--
Jay Hennigan - j...@west.net
Network Engineering - CCIE #7880
503 897-8550 - WB6RDV

Re: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-31 Thread Sabri Berisha

- On Aug 31, 2021, at 2:11 AM, Forrest Christian (List Account) 
li...@packetflux.com wrote:

Hi,

> I just wish the electrical code would permit or require certain low cost 
> things
> which make temporary generator connections more likely to be safe.

> For example, code requires most furnaces to be hardwired. But a furnace is one
> of the first things you want on a generator in an extended winter power 
> outage.
> If instead of hardwired, the code required plug and socket connections at each
> 120v furnace then Joe homeowner would be more likely to run an extension cord
> from his generator to his furnace instead of trying to rig up his generator
> with a suicide cord.

Now I'm wondering which jurisdiction you're talking about. I live in California
in a home which was finalized in 2019. As I'm the first owner, I was there when
the inspector went up into the attic and checked my HVAC. My HVAC has a plug in
power cord running into a regular household socket (all in the attic). The 
inspector didn't say a word about it and issued the occupancy permit.

My electrically powered oven is hardwired, but I guess that's because it 
requires
two 50amp breakers?

Thanks,

Sabri

Re: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-31 Thread Mel Beckman

It’s germane to NANOG. Just last week I visited a “data center” that uses a 
roll up generator and a cheater cord to power the racks. “Oh, this is safe”, 
they told me. “We have a policy that you must throw the main breaker before 
plugging in the generator. Since you have to open the garage door to wheel in 
the generator (!), you walk right by the switchgear and a sign that reminds you 
to throw the breaker.”

Code enforcement is on the way. :)

 -mel

On Aug 31, 2021, at 7:50 AM, Josh Luthman  wrote:

Is this conversation really taking place on NANOG?

Don't backfeed power.  Got it.  Stupid people are going to be stupid, we won't 
solve it here.

Josh Luthman
24/7 Help Desk: 937-552-2340
Direct: 937-552-2343
1100 Wayne St
Suite 1337
Troy, OH 45373

On Tue, Aug 31, 2021 at 10:41 AM Mel Beckman 
mailto:m...@beckman.org>> wrote:
Mark,

But you said “Gas-fired furnaces or heaters should not have an impact because 
the only electrical requirement is to fire up the pilot light.” There is no 
gas-fired furnace I know of that doesn’t require a blower fan. How else does 
the heat get out of the furnace?

To answer your question, you need to understand that this safety system has two 
components. The first component, the furnace interlock relay, is designed to 
interlock the blower with the forced-air system, which also includes an outside 
air supply valve. When the blower is energized, a circuit inside the furnace 
gets power. The blower and furnace operate continuously when this circuit is 
energized, and the supply valve opens and closes as needed to ensure the air 
doesn’t get stale.

The safety second component is the limit switch, which primarily turns the 
blower fan on and off, but also has a safety role. When the temperature in the 
air supply plenum gets too hot, the limit switch turns off the furnace burner 
(or boiler, in a water-based system) to prevent damage, and possibly a fire, 
from overheating.

The actual state mechanics are thus not as simple as “if the blower fails the 
furnace won’t light”. And it’s because of these complex state mechanics that 
furnace electricity is hard wired.

Without AC power, no furnace can operate in a power outage. So that’s certainly 
not “no impact” from a utility failure. But the many thousands of deaths that 
occurred in homes and offices before these safety systems were put into the 
code is why you need a generator transfer switch if you want heat (or A/C) in 
your home during an outage.

 -mel

> On Aug 31, 2021, at 7:15 AM, Mark Tinka  wrote:
>
> 
>
>> On 8/31/21 16:06, Mel Beckman wrote:
>>
>> I think you’re forgetting about the all-important blower fan in a gas-fired 
>> furnace.
>
> Well, I was referring to a pure electric furnace, not one that uses a blower 
> over a gas-fired one :-).
>
> In that case, the blower is not a major draw on power.
>
> But again, we don't have those things here, so :-).
>
>
>> That said, the reason the code requires furnaces to be hardwired is to 
>> ensure that the blower interlock system can’t be bypassed. An electrical 
>> interlock ties a heat recover ventilator to circulation air blower operation 
>> of a forced-air furnace system. This ensure that the blower circulates 
>> supply and return air within the structure. A plug-in power source leads to 
>> the possibility that this interlock could be accidentally defeated, 
>> resulting in an overheat within the flame box.
>
> Makes sense.
>
> Does this, then, mean that if the blower itself were to fail, the gas burner 
> would not light?
>
> Mark.

Re: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-31 Thread Warren Kumari

On Tue, Aug 31, 2021 at 10:44 AM Mel Beckman  wrote:

> Mark,
>
> But you said “Gas-fired furnaces or heaters should not have an impact
> because the only electrical requirement is to fire up the pilot light.”
> There is no gas-fired furnace I know of that doesn’t require a blower fan.
> How else does the heat get out of the furnace?
>
> To answer your question, you need to understand that this safety system
> has two components. The first component, the furnace interlock relay, is
> designed to interlock the blower with the forced-air system, which also
> includes an outside air supply valve. When the blower is energized, a
> circuit inside the furnace gets power. The blower and furnace operate
> continuously when this circuit is energized, and the supply valve opens and
> closes as needed to ensure the air doesn’t get stale.
>
> The safety second component is the limit switch, which primarily turns the
> blower fan on and off, but also has a safety role. When the temperature in
> the air supply plenum gets too hot, the limit switch turns off the furnace
> burner (or boiler, in a water-based system) to prevent damage, and possibly
> a fire, from overheating.
>
> The actual state mechanics are thus not as simple as “if the blower fails
> the furnace won’t light”. And it’s because of these complex state mechanics
> that furnace electricity is hard wired.
>
> Without AC power, no furnace can operate in a power outage.


Depending on what you mean by furnace -- in some places, the term is used
to cover basically any permanent (usually non-wood) heater. We have
something like this in a holiday/weekend property:
https://www.vermontcastings.com/products/radiance-direct-vent-gas-stove?page=Options

It has an (optional) blower motor on the back to help with circulating the
heat, and also plugs in to allow easier starting, but if mains power isn't
available it can still be started with 4 "D" cells, or, if you are willing
to scrummage around underneath (where all the spiders live!), you can hold
down an override switch and start it by clicking a piezo button (or, if you
really don't like the hair on your arm, with a match). Even without the
blower motor operating, it makes a surprising amount of heat, and also
looks purdy...

W
P.S: Yes, we've clearly gotten away from the "Don't plug a generator in
without a transfer switch, don't run a generator indoors, remember to test
your smoke alarms every N, brush yer teeth, eat an apple, regularly
exercise, drink plenty of water, etc., but sometimes it's nice to just have
a chat - I miss NANOG...)



> So that’s certainly not “no impact” from a utility failure. But the many
> thousands of deaths that occurred in homes and offices before these safety
> systems were put into the code is why you need a generator transfer switch
> if you want heat (or A/C) in your home during an outage.
>
>  -mel
>
> > On Aug 31, 2021, at 7:15 AM, Mark Tinka  wrote:
> >
> > 
> >
> >> On 8/31/21 16:06, Mel Beckman wrote:
> >>
> >> I think you’re forgetting about the all-important blower fan in a
> gas-fired furnace.
> >
> > Well, I was referring to a pure electric furnace, not one that uses a
> blower over a gas-fired one :-).
> >
> > In that case, the blower is not a major draw on power.
> >
> > But again, we don't have those things here, so :-).
> >
> >
> >> That said, the reason the code requires furnaces to be hardwired is to
> ensure that the blower interlock system can’t be bypassed. An electrical
> interlock ties a heat recover ventilator to circulation air blower
> operation of a forced-air furnace system. This ensure that the blower
> circulates supply and return air within the structure. A plug-in power
> source leads to the possibility that this interlock could be accidentally
> defeated, resulting in an overheat within the flame box.
> >
> > Makes sense.
> >
> > Does this, then, mean that if the blower itself were to fail, the gas
> burner would not light?
> >
> > Mark.
>


-- 
The computing scientist’s main challenge is not to get confused by the
complexities of his own making.
  -- E. W. Dijkstra

Re: Reminder: Never connect a generator to home wiring without transfer switch





On 8/31/21 16:41, Mel Beckman wrote:


But you said “Gas-fired furnaces or heaters should not have an impact because 
the only electrical requirement is to fire up the pilot light.” There is no 
gas-fired furnace I know of that doesn’t require a blower fan. How else does 
the heat get out of the furnace?


I was conceptualizing it the same way we have on-demand or tank-based 
gas water heaters here, where the heat is not distributed by a blower.


Like I said before, we don't generally use furnaces in this part of the 
world to heat homes. So I don't have experience with that :-).




To answer your question, you need to understand that this safety system has two 
components. The first component, the furnace interlock relay, is designed to 
interlock the blower with the forced-air system, which also includes an outside 
air supply valve. When the blower is energized, a circuit inside the furnace 
gets power. The blower and furnace operate continuously when this circuit is 
energized, and the supply valve opens and closes as needed to ensure the air 
doesn’t get stale.

The safety second component is the limit switch, which primarily turns the 
blower fan on and off, but also has a safety role. When the temperature in the 
air supply plenum gets too hot, the limit switch turns off the furnace burner 
(or boiler, in a water-based system) to prevent damage, and possibly a fire, 
from overheating.

The actual state mechanics are thus not as simple as “if the blower fails the 
furnace won’t light”. And it’s because of these complex state mechanics that 
furnace electricity is hard wired.


You learn something new everyday.

Thanks, Mel.



Without AC power, no furnace can operate in a power outage. So that’s certainly 
not “no impact” from a utility failure. But the many thousands of deaths that 
occurred in homes and offices before these safety systems were put into the 
code is why you need a generator transfer switch if you want heat (or A/C) in 
your home during an outage.


Makes sense.

My solar PV-based water heating system requires an AC reference to make 
solar power to energize the water tank element. If there is a loss of 
AC, it shuts off (not unlike a regular UL 1741-compliant PV inverter). 
To workaround that, I asked the vendor to add a UPS input, where I can 
attach a UPS that the system can use as a reference, to keep making 
solar power in the event of loss of grid mains. Of course, that was 
before I had whole-home backup, but it did the job during the gap.


Mark.

Re: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-31 Thread Josh Luthman

Is this conversation really taking place on NANOG?

Don't backfeed power.  Got it.  Stupid people are going to be stupid, we
won't solve it here.

Josh Luthman
24/7 Help Desk: 937-552-2340
Direct: 937-552-2343
1100 Wayne St
Suite 1337
Troy, OH 45373


On Tue, Aug 31, 2021 at 10:41 AM Mel Beckman  wrote:

> Mark,
>
> But you said “Gas-fired furnaces or heaters should not have an impact
> because the only electrical requirement is to fire up the pilot light.”
> There is no gas-fired furnace I know of that doesn’t require a blower fan.
> How else does the heat get out of the furnace?
>
> To answer your question, you need to understand that this safety system
> has two components. The first component, the furnace interlock relay, is
> designed to interlock the blower with the forced-air system, which also
> includes an outside air supply valve. When the blower is energized, a
> circuit inside the furnace gets power. The blower and furnace operate
> continuously when this circuit is energized, and the supply valve opens and
> closes as needed to ensure the air doesn’t get stale.
>
> The safety second component is the limit switch, which primarily turns the
> blower fan on and off, but also has a safety role. When the temperature in
> the air supply plenum gets too hot, the limit switch turns off the furnace
> burner (or boiler, in a water-based system) to prevent damage, and possibly
> a fire, from overheating.
>
> The actual state mechanics are thus not as simple as “if the blower fails
> the furnace won’t light”. And it’s because of these complex state mechanics
> that furnace electricity is hard wired.
>
> Without AC power, no furnace can operate in a power outage. So that’s
> certainly not “no impact” from a utility failure. But the many thousands of
> deaths that occurred in homes and offices before these safety systems were
> put into the code is why you need a generator transfer switch if you want
> heat (or A/C) in your home during an outage.
>
>  -mel
>
> > On Aug 31, 2021, at 7:15 AM, Mark Tinka  wrote:
> >
> > 
> >
> >> On 8/31/21 16:06, Mel Beckman wrote:
> >>
> >> I think you’re forgetting about the all-important blower fan in a
> gas-fired furnace.
> >
> > Well, I was referring to a pure electric furnace, not one that uses a
> blower over a gas-fired one :-).
> >
> > In that case, the blower is not a major draw on power.
> >
> > But again, we don't have those things here, so :-).
> >
> >
> >> That said, the reason the code requires furnaces to be hardwired is to
> ensure that the blower interlock system can’t be bypassed. An electrical
> interlock ties a heat recover ventilator to circulation air blower
> operation of a forced-air furnace system. This ensure that the blower
> circulates supply and return air within the structure. A plug-in power
> source leads to the possibility that this interlock could be accidentally
> defeated, resulting in an overheat within the flame box.
> >
> > Makes sense.
> >
> > Does this, then, mean that if the blower itself were to fail, the gas
> burner would not light?
> >
> > Mark.
>

Re: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-31 Thread Mel Beckman

Mark,

But you said “Gas-fired furnaces or heaters should not have an impact because 
the only electrical requirement is to fire up the pilot light.” There is no 
gas-fired furnace I know of that doesn’t require a blower fan. How else does 
the heat get out of the furnace?

To answer your question, you need to understand that this safety system has two 
components. The first component, the furnace interlock relay, is designed to 
interlock the blower with the forced-air system, which also includes an outside 
air supply valve. When the blower is energized, a circuit inside the furnace 
gets power. The blower and furnace operate continuously when this circuit is 
energized, and the supply valve opens and closes as needed to ensure the air 
doesn’t get stale.

The safety second component is the limit switch, which primarily turns the 
blower fan on and off, but also has a safety role. When the temperature in the 
air supply plenum gets too hot, the limit switch turns off the furnace burner 
(or boiler, in a water-based system) to prevent damage, and possibly a fire, 
from overheating.

The actual state mechanics are thus not as simple as “if the blower fails the 
furnace won’t light”. And it’s because of these complex state mechanics that 
furnace electricity is hard wired.

Without AC power, no furnace can operate in a power outage. So that’s certainly 
not “no impact” from a utility failure. But the many thousands of deaths that 
occurred in homes and offices before these safety systems were put into the 
code is why you need a generator transfer switch if you want heat (or A/C) in 
your home during an outage.

 -mel 

> On Aug 31, 2021, at 7:15 AM, Mark Tinka  wrote:
> 
> 
> 
>> On 8/31/21 16:06, Mel Beckman wrote:
>> 
>> I think you’re forgetting about the all-important blower fan in a gas-fired 
>> furnace.
> 
> Well, I was referring to a pure electric furnace, not one that uses a blower 
> over a gas-fired one :-).
> 
> In that case, the blower is not a major draw on power.
> 
> But again, we don't have those things here, so :-).
> 
> 
>> That said, the reason the code requires furnaces to be hardwired is to 
>> ensure that the blower interlock system can’t be bypassed. An electrical 
>> interlock ties a heat recover ventilator to circulation air blower operation 
>> of a forced-air furnace system. This ensure that the blower circulates 
>> supply and return air within the structure. A plug-in power source leads to 
>> the possibility that this interlock could be accidentally defeated, 
>> resulting in an overheat within the flame box.
> 
> Makes sense.
> 
> Does this, then, mean that if the blower itself were to fail, the gas burner 
> would not light?
> 
> Mark.

Re: Reminder: Never connect a generator to home wiring without transfer switch





On 8/31/21 16:06, Mel Beckman wrote:


I think you’re forgetting about the all-important blower fan in a gas-fired 
furnace.


Well, I was referring to a pure electric furnace, not one that uses a 
blower over a gas-fired one :-).


In that case, the blower is not a major draw on power.

But again, we don't have those things here, so :-).



That said, the reason the code requires furnaces to be hardwired is to ensure 
that the blower interlock system can’t be bypassed. An electrical interlock 
ties a heat recover ventilator to circulation air blower operation of a 
forced-air furnace system. This ensure that the blower circulates supply and 
return air within the structure. A plug-in power source leads to the 
possibility that this interlock could be accidentally defeated, resulting in an 
overheat within the flame box.


Makes sense.

Does this, then, mean that if the blower itself were to fail, the gas 
burner would not light?


Mark.

Re: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-31 Thread Mel Beckman

Mark,

I think you’re forgetting about the all-important blower fan in a gas-fired 
furnace.

That said, the reason the code requires furnaces to be hardwired is to ensure 
that the blower interlock system can’t be bypassed. An electrical interlock 
ties a heat recover ventilator to circulation air blower operation of a 
forced-air furnace system. This ensure that the blower circulates supply and 
return air within the structure. A plug-in power source leads to the 
possibility that this interlock could be accidentally defeated, resulting in an 
overheat within the flame box.

 -mel 

> On Aug 31, 2021, at 3:38 AM, Mark Tinka  wrote:
> 
> 
> 
>> On 8/31/21 12:26, Forrest Christian (List Account) wrote:
>> 
>> Yes.   Or any other furnace where the electricity is only used for 
>> circulation of the heat.  Gas fired Hot water furnaces would be another 
>> example where there is minimal electricity used to run the furnace controls 
>> and circulate the hot water.
> 
> Gas-fired furnaces or heaters should not have an impact because the only 
> electrical requirement is to fire up the pilot light.
> 
> But fully-electric heating has a much higher impact on energy sources (heat 
> pumps being the least).
> 
> I believe typical electric central furnaces are anywhere between 10kW - 15kW 
> systems. Would a standard 4kVA - 8kVA generator for average Jane cut it? Not 
> sure.
> 
> Then again, I live in a more forgiving climate, so I have a very limited need 
> to understand this better.
> 
> But I can understand why the code has not caught up to this yet, and insists 
> on hard-wiring the devices... because the majority of home and buildings will 
> still be using all-electric equipment that require plenty of energy, where 
> things can go wrong if you allow Jane to just run her suicide cord any way 
> she may like. Yes, there may be more folk moving over to other energy sources 
> that eliminate or reduce the need for electricity, but the code has to cater 
> for the wider demographic.
> 
> Mark.

Re: Reminder: Never connect a generator to home wiring without transfer switch





On 8/31/21 12:26, Forrest Christian (List Account) wrote:

Yes.   Or any other furnace where the electricity is only used for 
circulation of the heat.  Gas fired Hot water furnaces would be 
another example where there is minimal electricity used to run the 
furnace controls and circulate the hot water.


Gas-fired furnaces or heaters should not have an impact because the only 
electrical requirement is to fire up the pilot light.


But fully-electric heating has a much higher impact on energy sources 
(heat pumps being the least).


I believe typical electric central furnaces are anywhere between 10kW - 
15kW systems. Would a standard 4kVA - 8kVA generator for average Jane 
cut it? Not sure.


Then again, I live in a more forgiving climate, so I have a very limited 
need to understand this better.


But I can understand why the code has not caught up to this yet, and 
insists on hard-wiring the devices... because the majority of home and 
buildings will still be using all-electric equipment that require plenty 
of energy, where things can go wrong if you allow Jane to just run her 
suicide cord any way she may like. Yes, there may be more folk moving 
over to other energy sources that eliminate or reduce the need for 
electricity, but the code has to cater for the wider demographic.


Mark.

Re: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-31 Thread Forrest Christian (List Account)

Yes.   Or any other furnace where the electricity is only used for
circulation of the heat.  Gas fired Hot water furnaces would be another
example where there is minimal electricity used to run the furnace controls
and circulate the hot water.

All of these run on 120V and usually well under 15A.

It's silly that you are prohibited by code from installing a dedicated plug
and socket for these.

On Tue, Aug 31, 2021, 3:19 AM Mark Tinka  wrote:

>
>
> On 8/31/21 11:11, Forrest Christian (List Account) wrote:
>
> > I just wish the electrical code would permit or require certain low
> > cost things which make temporary generator connections more likely to
> > be safe.
> >
> > For example, code requires most furnaces to be hardwired.  But a
> > furnace is one of the first things you want on a generator in an
> > extended winter power outage.   If instead of hardwired, the code
> > required plug and socket connections at each 120v furnace  then Joe
> > homeowner would be more likely to run an extension cord from his
> > generator to his furnace instead of trying to rig up his generator
> > with a suicide cord.
>
> Are you referring to a forced-air central electric furnace?
>
> Mark.
>

Re: Reminder: Never connect a generator to home wiring without transfer switch





On 8/31/21 11:11, Forrest Christian (List Account) wrote:

I just wish the electrical code would permit or require certain low 
cost things which make temporary generator connections more likely to 
be safe.


For example, code requires most furnaces to be hardwired.  But a 
furnace is one of the first things you want on a generator in an 
extended winter power outage.   If instead of hardwired, the code 
required plug and socket connections at each 120v furnace  then Joe 
homeowner would be more likely to run an extension cord from his 
generator to his furnace instead of trying to rig up his generator 
with a suicide cord.


Are you referring to a forced-air central electric furnace?

Mark.

Re: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-31 Thread Forrest Christian (List Account)

I just wish the electrical code would permit or require certain low cost
things which make temporary generator connections more likely to be safe.

For example, code requires most furnaces to be hardwired.  But a furnace is
one of the first things you want on a generator in an extended winter power
outage.   If instead of hardwired, the code required plug and socket
connections at each 120v furnace  then Joe homeowner would be more likely
to run an extension cord from his generator to his furnace instead of
trying to rig up his generator with a suicide cord.

On Mon, Aug 30, 2021, 11:38 PM John van Oppen  wrote:

> I told my wife that she is my critical load as such I like to treat our
> place like a datacenter.   House wide UPS for all lights and all bedroom
> and office outlets, large generator system, ATS and lots of fuel.   Last
> time I was at a nanog and the power went out she chuckled when I told her
> it was out, she had just come home from work and driven right into the
> garage with all the lights on thinking the utility was still working.
>
> I did all my commissioning and calculations myself, even coordinated
> breakers for both sources into the sub panels, but I'm far from a home DIY
> when it comes to electrical.   My home 277/480v service is pretty cute
> compared to the stuff I normally play with and design.
>
> I've cabled my other portables into panels at people's houses before but I
> refuse to talk them through how to do it, if you don't know how to properly
> pull the utility breakers etc you have no business temping anything up, and
> making cables that make it easy is irresponsible safety wise.
>
> Power is serious business and mistakes can be very dangerous.
>
> The last few days has me feeling for all the folks keeping the hospitals
> and critical facilities running in Louisiana, seems like most made it
> through pretty well, huge testament to planning and the reliability of
> backup systems.
>
> -Original Message-
> From: NANOG  On Behalf Of Mark
> Tinka
> Sent: Wednesday, August 25, 2021 8:12 AM
> To: Jared Mauch 
> Cc: nanog@nanog.org
> Subject: Re: Reminder: Never connect a generator to home wiring without
> transfer switch
>
>
>
> On 8/25/21 16:59, Jared Mauch wrote:
>
> > This is why I personally spent the $$ on a proper standby generator with
> multiple ATS for the multiple panels.
>
> Same here.
>
> Massively painful, which led to some boring moments testing, testing and
> more testing. But after 5 months with electricians, electrical certifiers,
> battery vendors and inverter vendors (and a little voltage/amp sensor to
> capture slow voltage grid brownouts that kept tripping my battery), it's
> been solid for nearly a year. And looking good.
>
> I can now travel and not worry about the Mrs. waking me up from my sleep,
> on the far side of the world :-).
>
> Mark.
>

Re: Reminder: Never connect a generator to home wiring without transfer switch





On 8/31/21 07:37, John van Oppen wrote:

I told my wife that she is my critical load as such I like to treat our place 
like a datacenter.   House wide UPS for all lights and all bedroom and office 
outlets, large generator system, ATS and lots of fuel.   Last time I was at a 
nanog and the power went out she chuckled when I told her it was out, she had 
just come home from work and driven right into the garage with all the lights 
on thinking the utility was still working.


Me too :-).

She wasn't amused when all the contractors are faffing about for 8 
months installing the system. But she is pleased when the power goes out 
and we just keep going.




I did all my commissioning and calculations myself, even coordinated breakers 
for both sources into the sub panels, but I'm far from a home DIY when it comes 
to electrical.   My home 277/480v service is pretty cute compared to the stuff 
I normally play with and design.

I've cabled my other portables into panels at people's houses before but I 
refuse to talk them through how to do it, if you don't know how to properly 
pull the utility breakers etc you have no business temping anything up, and 
making cables that make it easy is irresponsible safety wise.

Power is serious business and mistakes can be very dangerous.


I did all my design and planning too, but used qualified contractors to 
install and certify the setup. I am not an electrician. I won't even 
replace a breaker panel cover label sticker myself. I don't play those 
games :-).


Mark.

RE: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-30 Thread John van Oppen

I told my wife that she is my critical load as such I like to treat our place 
like a datacenter.   House wide UPS for all lights and all bedroom and office 
outlets, large generator system, ATS and lots of fuel.   Last time I was at a 
nanog and the power went out she chuckled when I told her it was out, she had 
just come home from work and driven right into the garage with all the lights 
on thinking the utility was still working.

I did all my commissioning and calculations myself, even coordinated breakers 
for both sources into the sub panels, but I'm far from a home DIY when it comes 
to electrical.   My home 277/480v service is pretty cute compared to the stuff 
I normally play with and design.

I've cabled my other portables into panels at people's houses before but I 
refuse to talk them through how to do it, if you don't know how to properly 
pull the utility breakers etc you have no business temping anything up, and 
making cables that make it easy is irresponsible safety wise.

Power is serious business and mistakes can be very dangerous.

The last few days has me feeling for all the folks keeping the hospitals and 
critical facilities running in Louisiana, seems like most made it through 
pretty well, huge testament to planning and the reliability of backup systems.

-Original Message-
From: NANOG  On Behalf Of Mark Tinka
Sent: Wednesday, August 25, 2021 8:12 AM
To: Jared Mauch 
Cc: nanog@nanog.org
Subject: Re: Reminder: Never connect a generator to home wiring without 
transfer switch

On 8/25/21 16:59, Jared Mauch wrote:

> This is why I personally spent the $$ on a proper standby generator with 
> multiple ATS for the multiple panels.

Same here.

Massively painful, which led to some boring moments testing, testing and more 
testing. But after 5 months with electricians, electrical certifiers, battery 
vendors and inverter vendors (and a little voltage/amp sensor to capture slow 
voltage grid brownouts that kept tripping my battery), it's been solid for 
nearly a year. And looking good.

I can now travel and not worry about the Mrs. waking me up from my sleep, on 
the far side of the world :-).

Mark.

RE: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-30 Thread John van Oppen

Yes, most grounding out now that utilities do for work is all phases to one 
another, to the neutral and to the ground.

From: NANOG  On Behalf Of Mel Beckman
Sent: Monday, August 30, 2021 10:59 AM
To: Aaron C. de Bruyn 
Cc: NANOG Operators' Group 
Subject: Re: Reminder: Never connect a generator to home wiring without 
transfer switch

Aaron,

Your incorrect assumption is that lineman are tying phases to earth ground, a 
discontinued practice that killed many lineman up through 1980, despite its 
seeming faultless logic.

The current safety practice is called “equipotential grounding”, which doesn’t 
go to earth. Thus an backed can change the balance of potentials, resulting in 
lethal currents. As other have pointed out with real-word examples, this is a 
major safety issue, cause by the many “dumb enough” DIYers out there.

All explained elsewhere in the thread. I recommend you review the previous 
discussion, to avoid creating a NANOG bridge loop :)

 -mel

On Aug 30, 2021, at 9:43 AM, Aaron C. de Bruyn 
mailto:aa...@heyaaron.com>> wrote:

I've been following the thread.
If I'm dumb enough to back feed through the transformer into the downstream 
side of the downed line, how is it going to be a problem if linemen are 
grounding the phases on *both sides* of the work area.
That's what Ben seemed to be implying.

Re: Reminder: Never connect a generator to home wiring without transfer switch





On 8/30/21 21:20, Mel Beckman wrote:


I’ve had this scenario play out several times:


Gotta love the Internet - we are all experts :-).

Mark.

Re: Reminder: Never connect a generator to home wiring without transfer switch

I was catching 5 minutes of CNN earlier this morning down here, and Gov. 
Edwards (LA) was appealing to folk running generators to make sure they 
don't die from smoke inhalation, due to using them inside the house so 
as to keep them away from water. Apparently, many have died post-storm 
due to fume inhalation toxicity.


Perhaps advising folk not to run the units without a changeover switch 
might have been too much to ask, as well.


Thoughts and prayers for all the folk out in LA, this week.

Mark.

Re: Reminder: Never connect a generator to home wiring without transfer switch





On 8/30/21 22:13, Lamar Owen wrote:



I have some friends who work for the local electric cooperative, and 
all of them have backfeed stories.  Around here, which is very rural, 
it's not at all uncommon to have a single house isolated on a 
distribution spur; nor is it at all uncommon for some people to have 
the 'suicide dryer cord' 'ATS' in use.  One story I heard was that one 
individual had been a repeat offender, and several line workers had 
gotten bit (none were injured, thankfully) by his 4KVA generator; so 
after the repair of one outage, a line worker taught the individual a 
lesson by hitting the recloser without letting the individual know 
ahead of time (they had been letting the individual know that power 
was coming back on) and watching the individual's generator, out in 
his yard, explode from the out-of-sync condition.


As General Taylor in "Delta Force 2" used to lament, "Sh**! Always the 
hard way :-)".


    https://youtu.be/pJIGy4zHo6E?t=124

Mark.

Re: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-30 Thread Lamar Owen


On 8/25/21 11:26 AM, Dave wrote:
Back feed is a significant problem but bringing a generator that is 
not synchronized to the grid can have dramatic results, typically only 
once 


This, IMO, is a great thread, lots of good reading here.

My $dayjob is at a site where the previous occupants did indeed operate, 
under PE supervision and special permit from the electric cooperative, 
grid-synchronized generators.  Most of the required switchgear is still 
here, including the dual-incandescent-bulb sync indicators.  Since we 
don't have the required 24x7 PE (that's licensed Professional Engineer, 
by the way) supervision, we don't do this, but over a period of several 
years had normal ATS setups with isolated generation installed, with a 
more distributed setup with only critical loads on UPS.  But grid-sync 
generation is a form of UPS.


The process of going from grid being offline, then adjusting the 
generator governors to sync-in and closing the main breakers (three of 
them, 2,500A each) at the very instant of sync, was apparently quite the 
sight to behold, with the sync indicators blinking and pulsing, until 
they locked in  At the 2,500A level it is definitely not a pretty 
sight to reclose out of sync.


Synchronous generators were more reliable and less expensive in those 
days than battery backups, especially in the megawatt class, and if you 
only required intermittent uninterruptable power.  The largest battery 
backup on site was 500KVA and was a Piller motor-generator with a huge 
battery on the DC bus.  The total site drew a bit over 2MW on a normal 
day, and so loads were prioritized and during critical operations only 
the required generator capacity was brought online in synchronous mode.  
The main breakers were set up with power-loss instant trip; when we went 
ATS and regular generator operations (much much less load for us) we 
disabled the power-loss trip functions on the three 2,500A mains.


I have some friends who work for the local electric cooperative, and all 
of them have backfeed stories.  Around here, which is very rural, it's 
not at all uncommon to have a single house isolated on a distribution 
spur; nor is it at all uncommon for some people to have the 'suicide 
dryer cord' 'ATS' in use.  One story I heard was that one individual had 
been a repeat offender, and several line workers had gotten bit (none 
were injured, thankfully) by his 4KVA generator; so after the repair of 
one outage, a line worker taught the individual a lesson by hitting the 
recloser without letting the individual know ahead of time (they had 
been letting the individual know that power was coming back on) and 
watching the individual's generator, out in his yard, explode from the 
out-of-sync condition.

Re: Reminder: Never connect a generator to home wiring without transfer switch

> The point that several brought up is that doing so is not only a bad idea, 
> but that it simply won't work 

Jay,

I’ve had this scenario play out several times:

DIYguy: Check out my new generator! It’s big enough to power the whole house!

Me: You run extension cords from the generator to all your devices then?

DIYguy: No need! I built this special “suicide cord” I read about online in a 
prepper forum. I just plug that into any wall outlet and it powers the whole 
house!

Me: Um, you haven’t tested this, have you?

DIYguy: Sure. I fired up the generator and plugged the dryer into it. Works a 
treat!

Me: No, I mean your special cord. Have you tested that?

DIYguy: Hey, if it'll power the dryer, it’ll power my whole house. No need to 
test!

Me: Ok, first of all, that’s not a “suicide cord”. That’s a “homicide cord”. 
Second, …

The problem with this scenario is that the DIYguy never finds out that it won’t 
work, at least not until the trial. :)

 -mel


> On Aug 30, 2021, at 11:25 AM, Jay Hennigan  wrote:
> 
> On 8/30/21 10:46, Aaron C. de Bruyn via NANOG wrote:
> 
>> While they were waiting for a few more trucks to arrive with a replacement 
>> pole, I got to ask them a few questions.  They said it's standard practice 
>> for them to ground on both sides exactly for the reason that someone might 
>> accidentally connect a generator.  They open the nearest switch on the 
>> upstream side, test to make sure the line is dead, install grounds on all 
>> the wires, then test the downstream side and attach grounds to all the 
>> wires, effectively making the work zone an isolated segment.
> 
> I don't think anyone participating in this forum was remotely close to 
> suggesting that anyone connect a generator to home wiring without a transfer 
> switch in place. It's stupid and dangerous.
> 
> in the vast majority of power outage scenarios. Unless the outage is on your 
> service drop or on your pole pig, the impedance of the neighborhood or city 
> downstream of the outage as reflected through the transformers will vastly 
> overwhelm any portable generator capable of being connected with a "suicide 
> cord" by several orders of magnitude.
> 
> The other point is that, assuming that the utility is following their safety 
> protocols, the utility worker is going to ground the load side as well as the 
> incoming feed specifically to prevent backfeeding the grid from a miswired 
> generator.
> 
> Yes, never connect a generator to home wiring without a properly installed 
> transfer switch.
> 
> Yes, the utility workers should ground the load side to avoid being killed in 
> the event that someone does so.
> 
> Yes, if the utility follows all procedures correctly, and you happen to 
> connect your miswired generator at the exact instant that the utility worker 
> removes the ground after making the connection, and said worker grabs the 
> conductor with bare hands, and there's a path to ground through the worker's 
> body at that instant, that worker is probably going to die. The probability 
> of this happening is somewhat greater than that of winning the lottery, but 
> if they're on a pole in the middle of a storm working on overhead wires, the 
> odds of their being struck by lightning are also worth considering.
> 
> It's a warning worth repeating, but probably not to this extent.
> 
>>This is NANOG -- I'm sure that we've all followed a set of steps
>>perfectly and still managed to redistribute BGP into the IGP, or
>>apply an ACL and lock ourselves out of a box, or types "show run"
>>and watched the router randomly reboot. 
> 
> Don't forget the classic "switchport trunk allowed vlan" vs. "switchport 
> trunk allowed vlan add".
> 
> -- 
> Jay Hennigan - j...@west.net
> Network Engineering - CCIE #7880
> 503 897-8550 - WB6RDV

Re: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-30 Thread Jay Hennigan


On 8/30/21 10:46, Aaron C. de Bruyn via NANOG wrote:

While they were waiting for a few more trucks to arrive with a 
replacement pole, I got to ask them a few questions.  They said it's 
standard practice for them to ground on both sides exactly for the 
reason that someone might accidentally connect a generator.  They open 
the nearest switch on the upstream side, test to make sure the line is 
dead, install grounds on all the wires, then test the downstream side 
and attach grounds to all the wires, effectively making the work zone an 
isolated segment.


I don't think anyone participating in this forum was remotely close to 
suggesting that anyone connect a generator to home wiring without a 
transfer switch in place. It's stupid and dangerous.


The point that several brought up is that doing so is not only a bad 
idea, but that it simply won't work in the vast majority of power outage 
scenarios. Unless the outage is on your service drop or on your pole 
pig, the impedance of the neighborhood or city downstream of the outage 
as reflected through the transformers will vastly overwhelm any portable 
generator capable of being connected with a "suicide cord" by several 
orders of magnitude.


The other point is that, assuming that the utility is following their 
safety protocols, the utility worker is going to ground the load side as 
well as the incoming feed specifically to prevent backfeeding the grid 
from a miswired generator.


Yes, never connect a generator to home wiring without a properly 
installed transfer switch.


Yes, the utility workers should ground the load side to avoid being 
killed in the event that someone does so.


Yes, if the utility follows all procedures correctly, and you happen to 
connect your miswired generator at the exact instant that the utility 
worker removes the ground after making the connection, and said worker 
grabs the conductor with bare hands, and there's a path to ground 
through the worker's body at that instant, that worker is probably going 
to die. The probability of this happening is somewhat greater than that 
of winning the lottery, but if they're on a pole in the middle of a 
storm working on overhead wires, the odds of their being struck by 
lightning are also worth considering.


It's a warning worth repeating, but probably not to this extent.


This is NANOG -- I'm sure that we've all followed a set of steps
perfectly and still managed to redistribute BGP into the IGP, or
apply an ACL and lock ourselves out of a box, or types "show run"
and watched the router randomly reboot. 


Don't forget the classic "switchport trunk allowed vlan" vs. "switchport 
trunk allowed vlan add".


--
Jay Hennigan - j...@west.net
Network Engineering - CCIE #7880
503 897-8550 - WB6RDV

Re: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-30 Thread Warren Kumari

On Mon, Aug 30, 2021 at 1:57 PM Tom Beecher  wrote:

> There are usually redundancies built-in when it comes to safety.  i.e.
>> what's the point of installing grounds on the upstream side if you have the
>> switch open?  If the lines are de-energized, why wear gloves?  If you're
>> doing all that, why carry an AED?
>>
>
> My uncle was a high tension lineman for much of his career. He was
> frequently on response teams that went all over the country helping restore
> power after severe weather or natural disasters.
>
> There are not 'usually' redundancies. There are ALWAYS redundancies.
>

Yup - and even with this, "an average of 45 linemen a year loses their
lives in the line of duty, leaving families who depend on them." --
https://fallenlinemen.org/frequently-asked-questions/
The original point remains: "Reminder: Never connect a generator to home
wiring without transfer switch".


> Because in that world, especially doing restorations, there are rarely
> opportunities to learn from a mistake.
>

Indeed.
W


>
>
> On Mon, Aug 30, 2021 at 1:48 PM Aaron C. de Bruyn via NANOG <
> nanog@nanog.org> wrote:
>
>> During the February 2021 storm that swept through the US, power got
>> knocked out on my rural street due to a tree coming down and taking out a
>> pole.
>>
>> While they were waiting for a few more trucks to arrive with a
>> replacement pole, I got to ask them a few questions.  They said it's
>> standard practice for them to ground on both sides exactly for the reason
>> that someone might accidentally connect a generator.  They open the nearest
>> switch on the upstream side, test to make sure the line is dead, install
>> grounds on all the wires, then test the downstream side and attach grounds
>> to all the wires, effectively making the work zone an isolated segment.
>>
>> I doubt it's "if you follow every step perfectly at all times and never
>> make a mistake".
>> There are usually redundancies built-in when it comes to safety.  i.e.
>> what's the point of installing grounds on the upstream side if you have the
>> switch open?  If the lines are de-energized, why wear gloves?  If you're
>> doing all that, why carry an AED?
>>
>> -A
>>
>> On Mon, Aug 30, 2021 at 10:19 AM Warren Kumari  wrote:
>>
>>>
>>>
>>> On Mon, Aug 30, 2021 at 12:47 PM Aaron C. de Bruyn via NANOG <
>>> nanog@nanog.org> wrote:
>>>
 I've been following the thread.
 If I'm dumb enough to back feed through the transformer into the
 downstream side of the downed line, how is it going to be a problem if
 linemen are grounding the phases on *both sides* of the work area.

>>>
>>> I suspect that there is a non-zero amount of "in an ideal, perfect
>>> world, when all of the wires are simply lines on a piece of paper, and you
>>> can look at them from the comfort of your office chair, this is easy" -
>>> but, in the real world, linesmen are rushing about and trying to get the
>>> lights back on, cut through the big ash tree that is wedged between the oak
>>> and the pole, etc. Even the nice idea of "well, just take the conductos and
>>> tie 'em to ground" means that you need to go trudging through hedges and
>>> vegetation and tree limbs and lions and tigers and bears, often while it is
>>> pissing down with rain or baking hot.
>>>
>>> I guess I'm missing how we've moved from the "some people are putting
>>> their lives on the line, let's try to make their life less dangerous" into
>>> a "well... if they simply followed these set of steps perfectly at all
>>> times, and never made a mistake they'd be fine."
>>> This is NANOG -- I'm sure that we've all followed a set of steps
>>> perfectly and still managed to redistribute BGP into the IGP, or apply an
>>> ACL and lock ourselves out of a box, or types "show run" and watched the
>>> router randomly reboot. Now consider this, but with the added drama of
>>> potentially ending up dead...
>>>
>>> W
>>>
>>>
 That's what Ben seemed to be implying.

 -A

 On Mon, Aug 30, 2021 at 9:09 AM Mel Beckman  wrote:

> Aaron,
>
> If you read back in this thread (using the NANOG mailing list
> archive), you’ll find this has been explained in great detail. In a
> nutshell, phase grounding won’t help if a generator is energized from the
> customer end, and this technique was discontinued in the 1970s due to the
> many deaths that resulted.
>
>  -mel
>
> On Aug 30, 2021, at 9:02 AM, Aaron C. de Bruyn via NANOG <
> nanog@nanog.org> wrote:
>
> 
> On Mon, Aug 30, 2021 at 7:35 AM Lady Benjamin Cannon of Glencoe, ASCE <
> l...@6by7.net> wrote:
>
>> Yes, this is a real and dangerous problem.  Today.  Even with
>> grounding I’m afraid.  Source: I’ve been working in an engineering 
>> capacity
>> for 27 years and I have the license you’d need to build a nuclear power
>> plant.
>>
>
> Would you care to educate me on this?
> If you ground the phases on both sides of

Re: Reminder: Never connect a generator to home wiring without transfer switch

Aaron,

I think you didn’t get that the lineman was talking about equipotential 
grounding. The school of “waiting for a few more trucks to arrive” probably 
doesn’t get into the full depth of the subject :)

 -mel

On Aug 30, 2021, at 10:46 AM, Aaron C. de Bruyn 
mailto:aa...@heyaaron.com>> wrote:

During the February 2021 storm that swept through the US, power got knocked out 
on my rural street due to a tree coming down and taking out a pole.

While they were waiting for a few more trucks to arrive with a replacement 
pole, I got to ask them a few questions.  They said it's standard practice for 
them to ground on both sides exactly for the reason that someone might 
accidentally connect a generator.  They open the nearest switch on the upstream 
side, test to make sure the line is dead, install grounds on all the wires, 
then test the downstream side and attach grounds to all the wires, effectively 
making the work zone an isolated segment.

I doubt it's "if you follow every step perfectly at all times and never make a 
mistake".
There are usually redundancies built-in when it comes to safety.  i.e. what's 
the point of installing grounds on the upstream side if you have the switch 
open?  If the lines are de-energized, why wear gloves?  If you're doing all 
that, why carry an AED?

-A

On Mon, Aug 30, 2021 at 10:19 AM Warren Kumari 
mailto:war...@kumari.net>> wrote:


On Mon, Aug 30, 2021 at 12:47 PM Aaron C. de Bruyn via NANOG 
mailto:nanog@nanog.org>> wrote:
I've been following the thread.
If I'm dumb enough to back feed through the transformer into the downstream 
side of the downed line, how is it going to be a problem if linemen are 
grounding the phases on *both sides* of the work area.

I suspect that there is a non-zero amount of "in an ideal, perfect world, when 
all of the wires are simply lines on a piece of paper, and you can look at them 
from the comfort of your office chair, this is easy" - but, in the real world, 
linesmen are rushing about and trying to get the lights back on, cut through 
the big ash tree that is wedged between the oak and the pole, etc. Even the 
nice idea of "well, just take the conductos and tie 'em to ground" means that 
you need to go trudging through hedges and vegetation and tree limbs and lions 
and tigers and bears, often while it is pissing down with rain or baking hot.

I guess I'm missing how we've moved from the "some people are putting their 
lives on the line, let's try to make their life less dangerous" into a 
"well... if they simply followed these set of steps perfectly at all times, 
and never made a mistake they'd be fine."
This is NANOG -- I'm sure that we've all followed a set of steps perfectly and 
still managed to redistribute BGP into the IGP, or apply an ACL and lock 
ourselves out of a box, or types "show run" and watched the router randomly 
reboot. Now consider this, but with the added drama of potentially ending up 
dead...

W

That's what Ben seemed to be implying.

-A

On Mon, Aug 30, 2021 at 9:09 AM Mel Beckman 
mailto:m...@beckman.org>> wrote:
Aaron,

If you read back in this thread (using the NANOG mailing list archive), you’ll 
find this has been explained in great detail. In a nutshell, phase grounding 
won’t help if a generator is energized from the customer end, and this 
technique was discontinued in the 1970s due to the many deaths that resulted.

 -mel

On Aug 30, 2021, at 9:02 AM, Aaron C. de Bruyn via NANOG 
mailto:nanog@nanog.org>> wrote:


On Mon, Aug 30, 2021 at 7:35 AM Lady Benjamin Cannon of Glencoe, ASCE 
mailto:l...@6by7.net>> wrote:
Yes, this is a real and dangerous problem.  Today.  Even with grounding I’m 
afraid.  Source: I’ve been working in an engineering capacity for 27 years and 
I have the license you’d need to build a nuclear power plant.

Would you care to educate me on this?
If you ground the phases on both sides of the work-site, how are you going to 
end up being a better path to ground?

-A


--
The computing scientist’s main challenge is not to get confused by the
complexities of his own making.
  -- E. W. Dijkstra

Re: Reminder: Never connect a generator to home wiring without transfer switch

Aaron,

Your incorrect assumption is that lineman are tying phases to earth ground, a 
discontinued practice that killed many lineman up through 1980, despite its 
seeming faultless logic.

The current safety practice is called “equipotential grounding”, which doesn’t 
go to earth. Thus an backed can change the balance of potentials, resulting in 
lethal currents. As other have pointed out with real-word examples, this is a 
major safety issue, cause by the many “dumb enough” DIYers out there.

All explained elsewhere in the thread. I recommend you review the previous 
discussion, to avoid creating a NANOG bridge loop :)

 -mel

On Aug 30, 2021, at 9:43 AM, Aaron C. de Bruyn 
mailto:aa...@heyaaron.com>> wrote:

I've been following the thread.
If I'm dumb enough to back feed through the transformer into the downstream 
side of the downed line, how is it going to be a problem if linemen are 
grounding the phases on *both sides* of the work area.
That's what Ben seemed to be implying.

Re: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-30 Thread Tom Beecher

>
> There are usually redundancies built-in when it comes to safety.  i.e.
> what's the point of installing grounds on the upstream side if you have the
> switch open?  If the lines are de-energized, why wear gloves?  If you're
> doing all that, why carry an AED?
>

My uncle was a high tension lineman for much of his career. He was
frequently on response teams that went all over the country helping restore
power after severe weather or natural disasters.

There are not 'usually' redundancies. There are ALWAYS redundancies.
Because in that world, especially doing restorations, there are rarely
opportunities to learn from a mistake.

On Mon, Aug 30, 2021 at 1:48 PM Aaron C. de Bruyn via NANOG 
wrote:

> During the February 2021 storm that swept through the US, power got
> knocked out on my rural street due to a tree coming down and taking out a
> pole.
>
> While they were waiting for a few more trucks to arrive with a replacement
> pole, I got to ask them a few questions.  They said it's standard practice
> for them to ground on both sides exactly for the reason that someone might
> accidentally connect a generator.  They open the nearest switch on the
> upstream side, test to make sure the line is dead, install grounds on all
> the wires, then test the downstream side and attach grounds to all the
> wires, effectively making the work zone an isolated segment.
>
> I doubt it's "if you follow every step perfectly at all times and never
> make a mistake".
> There are usually redundancies built-in when it comes to safety.  i.e.
> what's the point of installing grounds on the upstream side if you have the
> switch open?  If the lines are de-energized, why wear gloves?  If you're
> doing all that, why carry an AED?
>
> -A
>
> On Mon, Aug 30, 2021 at 10:19 AM Warren Kumari  wrote:
>
>>
>>
>> On Mon, Aug 30, 2021 at 12:47 PM Aaron C. de Bruyn via NANOG <
>> nanog@nanog.org> wrote:
>>
>>> I've been following the thread.
>>> If I'm dumb enough to back feed through the transformer into the
>>> downstream side of the downed line, how is it going to be a problem if
>>> linemen are grounding the phases on *both sides* of the work area.
>>>
>>
>> I suspect that there is a non-zero amount of "in an ideal, perfect world,
>> when all of the wires are simply lines on a piece of paper, and you can
>> look at them from the comfort of your office chair, this is easy" - but, in
>> the real world, linesmen are rushing about and trying to get the lights
>> back on, cut through the big ash tree that is wedged between the oak and
>> the pole, etc. Even the nice idea of "well, just take the conductos and tie
>> 'em to ground" means that you need to go trudging through hedges and
>> vegetation and tree limbs and lions and tigers and bears, often while it is
>> pissing down with rain or baking hot.
>>
>> I guess I'm missing how we've moved from the "some people are putting
>> their lives on the line, let's try to make their life less dangerous" into
>> a "well... if they simply followed these set of steps perfectly at all
>> times, and never made a mistake they'd be fine."
>> This is NANOG -- I'm sure that we've all followed a set of steps
>> perfectly and still managed to redistribute BGP into the IGP, or apply an
>> ACL and lock ourselves out of a box, or types "show run" and watched the
>> router randomly reboot. Now consider this, but with the added drama of
>> potentially ending up dead...
>>
>> W
>>
>>
>>> That's what Ben seemed to be implying.
>>>
>>> -A
>>>
>>> On Mon, Aug 30, 2021 at 9:09 AM Mel Beckman  wrote:
>>>
 Aaron,

 If you read back in this thread (using the NANOG mailing list archive),
 you’ll find this has been explained in great detail. In a nutshell, phase
 grounding won’t help if a generator is energized from the customer end, and
 this technique was discontinued in the 1970s due to the many deaths that
 resulted.

  -mel

 On Aug 30, 2021, at 9:02 AM, Aaron C. de Bruyn via NANOG <
 nanog@nanog.org> wrote:

 
 On Mon, Aug 30, 2021 at 7:35 AM Lady Benjamin Cannon of Glencoe, ASCE <
 l...@6by7.net> wrote:

> Yes, this is a real and dangerous problem.  Today.  Even with
> grounding I’m afraid.  Source: I’ve been working in an engineering 
> capacity
> for 27 years and I have the license you’d need to build a nuclear power
> plant.
>

 Would you care to educate me on this?
 If you ground the phases on both sides of the work-site, how are you
 going to end up being a better path to ground?

 -A


>>
>> --
>> The computing scientist’s main challenge is not to get confused by the
>> complexities of his own making.
>>   -- E. W. Dijkstra
>>
>

Re: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-30 Thread Aaron C. de Bruyn via NANOG

During the February 2021 storm that swept through the US, power got knocked
out on my rural street due to a tree coming down and taking out a pole.

While they were waiting for a few more trucks to arrive with a replacement
pole, I got to ask them a few questions.  They said it's standard practice
for them to ground on both sides exactly for the reason that someone might
accidentally connect a generator.  They open the nearest switch on the
upstream side, test to make sure the line is dead, install grounds on all
the wires, then test the downstream side and attach grounds to all the
wires, effectively making the work zone an isolated segment.

I doubt it's "if you follow every step perfectly at all times and never
make a mistake".
There are usually redundancies built-in when it comes to safety.  i.e.
what's the point of installing grounds on the upstream side if you have the
switch open?  If the lines are de-energized, why wear gloves?  If you're
doing all that, why carry an AED?

-A

On Mon, Aug 30, 2021 at 10:19 AM Warren Kumari  wrote:

>
>
> On Mon, Aug 30, 2021 at 12:47 PM Aaron C. de Bruyn via NANOG <
> nanog@nanog.org> wrote:
>
>> I've been following the thread.
>> If I'm dumb enough to back feed through the transformer into the
>> downstream side of the downed line, how is it going to be a problem if
>> linemen are grounding the phases on *both sides* of the work area.
>>
>
> I suspect that there is a non-zero amount of "in an ideal, perfect world,
> when all of the wires are simply lines on a piece of paper, and you can
> look at them from the comfort of your office chair, this is easy" - but, in
> the real world, linesmen are rushing about and trying to get the lights
> back on, cut through the big ash tree that is wedged between the oak and
> the pole, etc. Even the nice idea of "well, just take the conductos and tie
> 'em to ground" means that you need to go trudging through hedges and
> vegetation and tree limbs and lions and tigers and bears, often while it is
> pissing down with rain or baking hot.
>
> I guess I'm missing how we've moved from the "some people are putting
> their lives on the line, let's try to make their life less dangerous" into
> a "well... if they simply followed these set of steps perfectly at all
> times, and never made a mistake they'd be fine."
> This is NANOG -- I'm sure that we've all followed a set of steps perfectly
> and still managed to redistribute BGP into the IGP, or apply an ACL and
> lock ourselves out of a box, or types "show run" and watched the router
> randomly reboot. Now consider this, but with the added drama of potentially
> ending up dead...
>
> W
>
>
>> That's what Ben seemed to be implying.
>>
>> -A
>>
>> On Mon, Aug 30, 2021 at 9:09 AM Mel Beckman  wrote:
>>
>>> Aaron,
>>>
>>> If you read back in this thread (using the NANOG mailing list archive),
>>> you’ll find this has been explained in great detail. In a nutshell, phase
>>> grounding won’t help if a generator is energized from the customer end, and
>>> this technique was discontinued in the 1970s due to the many deaths that
>>> resulted.
>>>
>>>  -mel
>>>
>>> On Aug 30, 2021, at 9:02 AM, Aaron C. de Bruyn via NANOG <
>>> nanog@nanog.org> wrote:
>>>
>>> 
>>> On Mon, Aug 30, 2021 at 7:35 AM Lady Benjamin Cannon of Glencoe, ASCE <
>>> l...@6by7.net> wrote:
>>>
 Yes, this is a real and dangerous problem.  Today.  Even with grounding
 I’m afraid.  Source: I’ve been working in an engineering capacity for 27
 years and I have the license you’d need to build a nuclear power plant.

>>>
>>> Would you care to educate me on this?
>>> If you ground the phases on both sides of the work-site, how are you
>>> going to end up being a better path to ground?
>>>
>>> -A
>>>
>>>
>
> --
> The computing scientist’s main challenge is not to get confused by the
> complexities of his own making.
>   -- E. W. Dijkstra
>

Re: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-30 Thread Warren Kumari

On Mon, Aug 30, 2021 at 12:47 PM Aaron C. de Bruyn via NANOG <
nanog@nanog.org> wrote:

> I've been following the thread.
> If I'm dumb enough to back feed through the transformer into the
> downstream side of the downed line, how is it going to be a problem if
> linemen are grounding the phases on *both sides* of the work area.
>

I suspect that there is a non-zero amount of "in an ideal, perfect world,
when all of the wires are simply lines on a piece of paper, and you can
look at them from the comfort of your office chair, this is easy" - but, in
the real world, linesmen are rushing about and trying to get the lights
back on, cut through the big ash tree that is wedged between the oak and
the pole, etc. Even the nice idea of "well, just take the conductos and tie
'em to ground" means that you need to go trudging through hedges and
vegetation and tree limbs and lions and tigers and bears, often while it is
pissing down with rain or baking hot.

I guess I'm missing how we've moved from the "some people are putting their
lives on the line, let's try to make their life less dangerous" into a
"well... if they simply followed these set of steps perfectly at all
times, and never made a mistake they'd be fine."
This is NANOG -- I'm sure that we've all followed a set of steps perfectly
and still managed to redistribute BGP into the IGP, or apply an ACL and
lock ourselves out of a box, or types "show run" and watched the router
randomly reboot. Now consider this, but with the added drama of potentially
ending up dead...

W

> That's what Ben seemed to be implying.
>
> -A
>
> On Mon, Aug 30, 2021 at 9:09 AM Mel Beckman  wrote:
>
>> Aaron,
>>
>> If you read back in this thread (using the NANOG mailing list archive),
>> you’ll find this has been explained in great detail. In a nutshell, phase
>> grounding won’t help if a generator is energized from the customer end, and
>> this technique was discontinued in the 1970s due to the many deaths that
>> resulted.
>>
>>  -mel
>>
>> On Aug 30, 2021, at 9:02 AM, Aaron C. de Bruyn via NANOG 
>> wrote:
>>
>> 
>> On Mon, Aug 30, 2021 at 7:35 AM Lady Benjamin Cannon of Glencoe, ASCE <
>> l...@6by7.net> wrote:
>>
>>> Yes, this is a real and dangerous problem.  Today.  Even with grounding
>>> I’m afraid.  Source: I’ve been working in an engineering capacity for 27
>>> years and I have the license you’d need to build a nuclear power plant.
>>>
>>
>> Would you care to educate me on this?
>> If you ground the phases on both sides of the work-site, how are you
>> going to end up being a better path to ground?
>>
>> -A
>>
>>

-- 
The computing scientist’s main challenge is not to get confused by the
complexities of his own making.
  -- E. W. Dijkstra

Re: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-30 Thread Aaron C. de Bruyn via NANOG

I've been following the thread.
If I'm dumb enough to back feed through the transformer into the downstream
side of the downed line, how is it going to be a problem if linemen are
grounding the phases on *both sides* of the work area.
That's what Ben seemed to be implying.

-A

On Mon, Aug 30, 2021 at 9:09 AM Mel Beckman  wrote:

> Aaron,
>
> If you read back in this thread (using the NANOG mailing list archive),
> you’ll find this has been explained in great detail. In a nutshell, phase
> grounding won’t help if a generator is energized from the customer end, and
> this technique was discontinued in the 1970s due to the many deaths that
> resulted.
>
>  -mel
>
> On Aug 30, 2021, at 9:02 AM, Aaron C. de Bruyn via NANOG 
> wrote:
>
> 
> On Mon, Aug 30, 2021 at 7:35 AM Lady Benjamin Cannon of Glencoe, ASCE <
> l...@6by7.net> wrote:
>
>> Yes, this is a real and dangerous problem.  Today.  Even with grounding
>> I’m afraid.  Source: I’ve been working in an engineering capacity for 27
>> years and I have the license you’d need to build a nuclear power plant.
>>
>
> Would you care to educate me on this?
> If you ground the phases on both sides of the work-site, how are you going
> to end up being a better path to ground?
>
> -A
>
>

Re: Reminder: Never connect a generator to home wiring without transfer switch





On 8/30/21 18:19, Chris Cariffe wrote:


That's a ground loop, you want to avoid that.


Yes, that...

Mark.

Re: Reminder: Never connect a generator to home wiring without transfer switch





On 8/30/21 18:20, Herb L wrote:


https://www.csemag.com/articles/grounding-points-single-or-multi/


Even they conclude that multiple grounding points should all converge at 
the main single point.


Grounding is probably the most misunderstood element of electricity. In 
cases where earth and neutral may be bonded, grounding at more than one 
point is generally ill-advised.


Mark.

Re: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-30 Thread Herb L

https://www.csemag.com/articles/grounding-points-single-or-multi/

> On Aug 30, 2021, at 09:10, Mark Tinka  wrote:
> 
> 
> 
> On 8/30/21 17:59, Aaron C. de Bruyn via NANOG wrote:
> 
>> 
>> Would you care to educate me on this?
>> If you ground the phases on both sides of the work-site, how are you going 
>> to end up being a better path to ground?
> 
> I'm not sure if it applies to work sites for linesmen, but my limited 
> understanding is that you don't generally want to ground at more than one 
> point.
> 
> Mark.

Re: Reminder: Never connect a generator to home wiring without transfer switch




On 8/30/21 17:59, Aaron C. de Bruyn via NANOG wrote:



Would you care to educate me on this?
If you ground the phases on both sides of the work-site, how are you 
going to end up being a better path to ground?


I'm not sure if it applies to work sites for linesmen, but my limited 
understanding is that you don't generally want to ground at more than 
one point.


Mark.

Re: Reminder: Never connect a generator to home wiring without transfer switch

Aaron,

If you read back in this thread (using the NANOG mailing list archive), you’ll 
find this has been explained in great detail. In a nutshell, phase grounding 
won’t help if a generator is energized from the customer end, and this 
technique was discontinued in the 1970s due to the many deaths that resulted.

 -mel

On Aug 30, 2021, at 9:02 AM, Aaron C. de Bruyn via NANOG  
wrote:


On Mon, Aug 30, 2021 at 7:35 AM Lady Benjamin Cannon of Glencoe, ASCE 
mailto:l...@6by7.net>> wrote:
Yes, this is a real and dangerous problem.  Today.  Even with grounding I’m 
afraid.  Source: I’ve been working in an engineering capacity for 27 years and 
I have the license you’d need to build a nuclear power plant.

Would you care to educate me on this?
If you ground the phases on both sides of the work-site, how are you going to 
end up being a better path to ground?

-A

Re: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-30 Thread Aaron C. de Bruyn via NANOG

On Mon, Aug 30, 2021 at 7:35 AM Lady Benjamin Cannon of Glencoe, ASCE <
l...@6by7.net> wrote:

> Yes, this is a real and dangerous problem.  Today.  Even with grounding
> I’m afraid.  Source: I’ve been working in an engineering capacity for 27
> years and I have the license you’d need to build a nuclear power plant.
>

Would you care to educate me on this?
If you ground the phases on both sides of the work-site, how are you going
to end up being a better path to ground?

-A

Re: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-30 Thread Lady Benjamin Cannon of Glencoe, ASCE

Yes, this is a real and dangerous problem.  Today.  Even with grounding I’m 
afraid.  Source: I’ve been working in an engineering capacity for 27 years and 
I have the license you’d need to build a nuclear power plant. 

Things people underestimate in my opinion: Water.  Wind.  Transformers.  
Earthquakes.
—L.B.

Ms. Lady Benjamin PD Cannon of Glencoe, ASCE
6x7 Networks & 6x7 Telecom, LLC 
CEO 
l...@6by7.net 
"The only fully end-to-end encrypted global telecommunications company in the 
world.”
FCC License KJ6FJJ

> On Aug 25, 2021, at 12:22 PM, Jay Hennigan  wrote:
> 
> On 8/25/21 12:03, Jay Nugent wrote:
>> Greetings,
>> And in that moment before the circuit breaker on your generator trips, 
>> your 120/240 volts has been stepped up to 7200 through the "pole pig" 
>> transformer in your neighborhood, and has KILLED the lineman working to fix 
>> that 7200 feeder circuit.
>>It only takes a MOMENT to stop someone's heart through electocution. It 
>> takes several milliseconds to pop a breaker.
> 
> And it would have only taken that lineman a few seconds to attach a grounding 
> bond to the supposedly dead feeder and transformer before grabbing it 
> bare-handed while speculating as to why it sounds like there's an engine 
> running at constant RPM coming from the house connected to the service drop.
> 
> Serious accidents are often caused not by a single failure but several.
> 
> -- 
> Jay Hennigan - j...@west.net
> Network Engineering - CCIE #7880
> 503 897-8550 - WB6RDV

Re: Reminder: Never connect a generator to home wiring without transfer switch




On 8/25/21 21:09, Warren Kumari wrote:



... and my "funny" story.

We used to live in San Jose. There was a large heat-wave, and much of 
SJC lost power because of A/C load, etc. Anyway, my wife and I go and 
camp in one of the office conference rooms for a few days because the 
office still has power and A/C.
Eventually PG claims that power is back on our street, so we drive 
back to San Jose and... no power. I flag down a passing PG truck and 
ask if they know when it will *really* be back. Lineman says that it 
is. I say it isn't. He says it is. I say it isn't.
He gets annoyed, opens up the pedestal box and sticks a meter in it, 
and agrees that I have no power. He then sticks the meter across the 
800A fuse, and discovers that the fuse blew.
"Ah. I can fix that fer you..." he says, and goes to the back of the 
truck... "Doh. I'm out of 800A fuses. Um er well, here is a 
6,000A fuse, that'll do..."


I briefly question the logic of this (presumably the lines in the 
ground are sized somewhere around 800-1,200A), but he says that 
this'll do, and he'll come back in the next few days to replace it. I 
lived there for another 8 or so months, and it was never replaced, 
but, well,... not my wires, so, um ¯\_(ツ)_/¯ I guess...


You annoyed him enough to give you a larger fuse, and be done with you :-).

Obviously, a safety hazard all on its own.

Mark.

Re: Reminder: Never connect a generator to home wiring without transfer switch





On 8/25/21 20:15, Lady Benjamin Cannon of Glencoe, ASCE wrote:


So the issue here is even a small 120vac current becomes a very fatal event at 
7.2 or 11 or 14.4kV.  It’s a safety issue for linepersons doing emergency 
restoration work.


Yep, because the home generator will be boosted up by the neighborhood 
transformer, in the back-feed direction.


Mark.

Re: Reminder: Never connect a generator to home wiring without transfer switch





On 8/25/21 20:30, b...@theworld.com wrote:


Ok, I'll be the curmudgeon...

Is this really a problem in practice?


The issue is that "it can be".

Solar inverter OEM's have long argued that UL 1741 is too stringent 
because the assumption is that linesmen always check for voltage on the 
line before working on it.


Multiple layers of protection are the way to go here. Just as in our 
industry, just a route-map may not be enough. A route-map + prefix list 
is a better plan.


Mark.

Re: Reminder: Never connect a generator to home wiring without transfer switch





On 8/25/21 19:25, Mel Beckman wrote:


Jay,

No, because transformers work in both directions :)

Plus, to the previous commenter that talked about “suicide cords”: 
they’’re more correctly termed “homicide  cords”:


“ The lineman killed yesterday was working for Pike Electric and 
picked up a line that was connected to someones house that hooked up a 
generator and did not disconnect from the distribution system. The 
linemans name was Ronnie Adams, age unknown. He had two children and a 
wife. As far as I know he was from Louisiana. They are trying to set 
up a fund for his family, but nothing I have heard of yet. I will let 
yall know more as I hear of it. I wish they would really teach folks 
the proper connection of generators, this was a really tragic and 
preventable accident. Stay Safe and think about it before you do it.”


https://powerlineman.com/lforum/showthread.php?711-Storm-Death 



Oh dear. This is sad.

There are some people that say UL 1741 is draconian because, in general, 
linesmen ALWAYS check wires before they start working on them. Even if 
they did before and there was no voltage, it could easily happen after 
the fact :-(...


Mark.

Re: Reminder: Never connect a generator to home wiring without transfer switch





On 8/25/21 19:21, Sabri Berisha wrote:


At my home, I use this: https://www.amazon.com/gp/product/B00CONE4MG

The interlock kit is installed in such a way that either the main or
the generator circuit breaker is closed. If the main is on, you can't
switch to generator power, and vice versa (see the pictures on the
listing, mine is installed the exact same way).


Yes, I've seen these on some Youtube videos. Work great.

Mark.

Re: Reminder: Never connect a generator to home wiring without transfer switch





On 8/25/21 19:10, Jay Hennigan wrote:



If you fail to isolate your generator from the incoming utility feed 
so that you're back-feeding the utility and the power is out for your 
neighborhood or the whole city, would not the load of trying to light 
up the whole town completely overwhelm your little generator to the 
point that it fails, stalls, or trips its own output breaker?


Long answered.

Mark.

Re: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-25 Thread Mel Beckman

Matt,

The practice you describe, called “parallel grounding”, was flawed and
discontinued in the 1970s. It was replaced by equipotential grounding, which
protects against accidental grid-delivered voltages, but still can’t protect
against customer-delivered voltages.

https://www.leafelectricalsafety.com/blog/electrical-safety/equipotential-grounding-versus-parallel-grounding

-mel beckman

On Aug 25, 2021, at 5:31 PM, Amir Herzberg wrote:

In theory, Jay is correct, but assuming that theory will always work in
practice is, in this case, how linemen end up dead. We're all well aware of
never assuming theory = practice, but admittedly the stakes tend to be a little
lower in our world.

right. my grandpa was a high-voltage/wattage engineer. He always said, `an
engineer can make an error, but only once'.

Luckily, we can make many errors :)

--
Amir Herzberg

Comcast professor of Security Innovations, Computer Science and Engineering,
University of Connecticut
Homepage: https://sites.google.com/site/amirherzberg/home
`Applied Introduction to Cryptography' textbook and lectures:
https://sites.google.com/site/amirherzberg/applied-crypto-textbook

On Wed, Aug 25, 2021 at 1:55 PM Matt Erculiani
mailto:merculi...@gmail.com>> wrote:
In theory, Jay is correct, but assuming that theory will always work in
practice is, in this case, how linemen end up dead. We're all well aware of
never assuming theory = practice, but admittedly the stakes tend to be a little
lower in our world.

Ensuring that a generator physically cannot backfeed is just one layer of
protection against the already very high risk of the job of a lineman. Then
there is, of course, checking for the presence of voltage before starting work,
but it's possible for a generator to start AFTER this check.

Another layer of protection is grounding all conductors prior to beginning
work, so that if power does come back (via the grid or a backfeed) A: The
lineman and bucket is not the best path to ground and B: The source is tripped.

Reading through that forum post, it sounds like that particular contractor had
a reputation for lacking proper safety precautions, so one or more safety
layers may have been removed, making the risk/impact of any single mistake much
greater than it should be.

-Matt

On Wed, Aug 25, 2021 at 11:25 AM Mel Beckman
mailto:m...@beckman.org>> wrote:
Jay,

No, because transformers work in both directions :)

Plus, to the previous commenter that talked about “suicide cords”: they’’re
more correctly termed “homicide cords”:

“ The lineman killed yesterday was working for Pike Electric and picked up a
line that was connected to someones house that hooked up a generator and did
not disconnect from the distribution system. The linemans name was Ronnie
Adams, age unknown. He had two children and a wife. As far as I know he was
from Louisiana. They are trying to set up a fund for his family, but nothing I
have heard of yet. I will let yall know more as I hear of it. I wish they would
really teach folks the proper connection of generators, this was a really
tragic and preventable accident. Stay Safe and think about it before you do it.”

https://powerlineman.com/lforum/showthread.php?711-Storm-Death

-mel

On Aug 25, 2021, at 10:12 AM, Jay Hennigan
mailto:j...@west.net>> wrote:

On 8/25/21 07:04, Mark Tinka wrote:
On 8/25/21 15:59, Ethan O'Toole wrote:

How would this not load the generator or inverter into oblivion?
Not sure I understand your question. Say again, please.

If you fail to isolate your generator from the incoming utility feed so that
you're back-feeding the utility and the power is out for your neighborhood or
the whole city, would not the load of trying to light up the whole town
completely overwhelm your little generator to the point that it fails, stalls,
or trips its own output breaker?

--
Jay Hennigan - j...@west.net
Network Engineering - CCIE #7880
503 897-8550 - WB6RDV

--
Matt Erculiani
ERCUL-ARIN

Re: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-25 Thread Amir Herzberg

>
> In theory, Jay is correct, but assuming that theory will always work in
> practice is, in this case, how linemen end up dead. We're all well aware of
> never assuming theory = practice, but admittedly the stakes tend to be a
> little lower in our world.
>

right. my grandpa was a high-voltage/wattage engineer. He always said, `an
engineer can make an error, but only once'.

Luckily, we can make many errors :)

-- 
Amir Herzberg

Comcast professor of Security Innovations, Computer Science and
Engineering, University of Connecticut
Homepage: https://sites.google.com/site/amirherzberg/home
`Applied Introduction to Cryptography' textbook and lectures:
 https://sites.google.com/site/amirherzberg/applied-crypto-textbook





On Wed, Aug 25, 2021 at 1:55 PM Matt Erculiani  wrote:

> In theory, Jay is correct, but assuming that theory will always work in
> practice is, in this case, how linemen end up dead. We're all well aware of
> never assuming theory = practice, but admittedly the stakes tend to be a
> little lower in our world.
>
> Ensuring that a generator physically cannot backfeed is just one layer of
> protection against the already very high risk of the job of a lineman. Then
> there is, of course, checking for the presence of voltage before starting
> work, but it's possible for a generator to start AFTER this check.
>
> Another layer of protection is grounding all conductors prior to beginning
> work, so that if power does come back (via the grid or a backfeed) A: The
> lineman and bucket is not the best path to ground and B: The source is
> tripped.
>
> Reading through that forum post, it sounds like that particular contractor
> had a reputation for lacking proper safety precautions, so one or more
> safety layers may have been removed, making the risk/impact of any single
> mistake much greater than it should be.
>
> -Matt
>
> On Wed, Aug 25, 2021 at 11:25 AM Mel Beckman  wrote:
>
>> Jay,
>>
>> No, because transformers work in both directions :)
>>
>> Plus, to the previous commenter that talked about “suicide cords”:
>> they’’re more correctly termed “homicide  cords”:
>>
>> “ The lineman killed yesterday was working for Pike Electric and picked
>> up a line that was connected to someones house that hooked up a generator
>> and did not disconnect from the distribution system. The linemans name was
>> Ronnie Adams, age unknown. He had two children and a wife. As far as I know
>> he was from Louisiana. They are trying to set up a fund for his family, but
>> nothing I have heard of yet. I will let yall know more as I hear of it. I
>> wish they would really teach folks the proper connection of generators,
>> this was a really tragic and preventable accident. Stay Safe and think
>> about it before you do it.”
>>
>> https://powerlineman.com/lforum/showthread.php?711-Storm-Death
>>
>>  -mel
>>
>> On Aug 25, 2021, at 10:12 AM, Jay Hennigan  wrote:
>>
>> On 8/25/21 07:04, Mark Tinka wrote:
>>
>> On 8/25/21 15:59, Ethan O'Toole wrote:
>>
>>
>> How would this not load the generator or inverter into oblivion?
>>
>> Not sure I understand your question. Say again, please.
>>
>>
>> If you fail to isolate your generator from the incoming utility feed so
>> that you're back-feeding the utility and the power is out for your
>> neighborhood or the whole city, would not the load of trying to light up
>> the whole town completely overwhelm your little generator to the point that
>> it fails, stalls, or trips its own output breaker?
>>
>> --
>> Jay Hennigan - j...@west.net
>> Network Engineering - CCIE #7880
>> 503 897-8550 - WB6RDV
>>
>>
>
> --
> Matt Erculiani
> ERCUL-ARIN
>

Re: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-25 Thread Chris Boyd

> On Aug 25, 2021, at 1:30 PM, b...@theworld.com wrote:
> 
> 
> 
> Except maybe that one guy at Harvard who came to replace what turned
> out to be a 100+ year old, home made, "breaker" which fed our machine
> room which was hidden in a narrow dark hallway winding around our
> machine room behind an unmarked metal, locked doorway. I had no idea
> it existed but we had no power so I called for help.
> 
> It was just a single copper bar about the size of a small candy bar
> tensioned into hot clips. Probably 400A but who remembers.
> 
> He removed the old one confidently enough, grabbed the new one with
> rubber-handled pliers and gloves and...
> 
>  Him: Have you ever played football?
> 
>  Me: Actually, yes, I have, why?
> 
>  Him: If something doesn't look right when I put this thing in just
>  tackle me clear of it as hard and as fast as you can.
> 
>  Me: Um, ok.
> 
> It all worked out fine and I wrote a memo that maybe Harvard could
> spring for a proper $500 breaker box?
> 
> 

When I was working at the MCI training facility in 1994, I went into the power 
facility classroom where they had battery strings, rectifiers, transfer 
switches, etc for students to learn on. I noticed that every 8-10 feet there 
was an 8 foot long 3/4 inch PVC pipe with about 16 feet of rope threaded 
through it. When I asked what those were for, the instructor said “We will use 
those to pull people off the electricity in case anyone gets shocked.”

I never heard that they were used, so that’s good.

—Chris

Re: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-25 Thread Haudy Kazemi via NANOG

It's the specific combination of current and voltage that is hazardous.

Too much current, through/across the heart, is the main, potentially fatal,
hazard. This is why 120v GFCIs trip near 5 milliamps (mA). (20-30 mA in the
wrong place is too much.)

A voltage pushes a current through a resistance, be that insulation or skin
or soil.

A 12 volt car battery can produce several hundred amps current, enough to
weld, if the terminals are shorted together, but a 12 volt battery doesn't
have a high enough voltage to push that current through dry skin. It isn't
dangerous to touch a single battery with dry hands.

Static electricity can be thousands of volts, but at extremely low current.
We feel it as the voltage is high enough, but it isn't actually dangerous
(to people; electronic equipment is another matter).

Holding the current constant at the danger threshold (20 mA), we can also
look at the power levels for various voltages.

20mA at 120v = 2.4 watts. On the other side of the transformer, 20 mA at
7200v = 144 watts. Conclusion: a single small 150 watt inverter is powerful
enough to be create a hazard for linemen working on an islanded section of
7200v powerline.

There are several categories of electrical hazards, as delineated by
voltage. Under 50v is generally considered to not be a shock hazard. More
details on voltage categories:
https://eecoonline.com/determining-safe-distances-from-electrical-hazards/

More details on GFCIs:
https://en.wikipedia.org/wiki/Residual-current_device

On Wed, Aug 25, 2021, 13:16 Lady Benjamin Cannon of Glencoe, ASCE <
l...@6by7.net> wrote:

> So the issue here is even a small 120vac current becomes a very fatal
> event at 7.2 or 11 or 14.4kV.  It’s a safety issue for linepersons doing
> emergency restoration work.
>
>
>
> Ms. Lady Benjamin PD Cannon of Glencoe, ASCE
> 6x7 Networks & 6x7 Telecom, LLC
> CEO
> l...@6by7.net
> "The only fully end-to-end encrypted global telecommunications company in
> the world.”
>
> FCC License KJ6FJJ
>
> Sent from my iPhone via RFC1149.
>
> > On Aug 25, 2021, at 7:24 AM, Ethan O'Toole  wrote:
> >
> > 
> >>
> >>> How would this not load the generator or inverter into oblivion?
> >> Not sure I understand your question. Say again, please.
> >
> > If you hook 100KW of neighbors up to your 5KW/20% THD garden generator
> it would probably trip the breaker, or stall.
> >
> > I suppose it could be an issue if it was a single house on a branch
> where the break being serviced was just that branch (rural customers.)
> >
> > Was just curious why it wouldn't overload the generator trying to power
> all the neighbors houses if connected to the grid.
> >
> >- Ethan
> >
>

Re: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-25 Thread Jay Hennigan


On 8/25/21 12:03, Jay Nugent wrote:

Greetings,
     And in that moment before the circuit breaker on your generator 
trips, your 120/240 volts has been stepped up to 7200 through the "pole 
pig" transformer in your neighborhood, and has KILLED the lineman 
working to fix that 7200 feeder circuit.


    It only takes a MOMENT to stop someone's heart through electocution. 
It takes several milliseconds to pop a breaker.


And it would have only taken that lineman a few seconds to attach a 
grounding bond to the supposedly dead feeder and transformer before 
grabbing it bare-handed while speculating as to why it sounds like 
there's an engine running at constant RPM coming from the house 
connected to the service drop.


Serious accidents are often caused not by a single failure but several.

--
Jay Hennigan - j...@west.net
Network Engineering - CCIE #7880
503 897-8550 - WB6RDV

Re: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-25 Thread Warren Kumari

On Wed, Aug 25, 2021 at 2:34 PM  wrote:

>
> Ok, I'll be the curmudgeon...
>
> Is this really a problem in practice?
>
> Most people I've known who worked around electrical mains etc assumed
> the worst at all times and it isn't all that difficult to protect
> against as one works.
>
> I realize one can infinitely invoke "better safe than sorry!", "an
> ounce of prevention...!"
>
> 

> Except maybe that one guy at Harvard who came to replace what turned
> out to be a 100+ year old, home made, "breaker" which fed our machine
> room which was hidden in a narrow dark hallway winding around our
> machine room behind an unmarked metal, locked doorway. I had no idea
> it existed but we had no power so I called for help.
>
> It was just a single copper bar about the size of a small candy bar
> tensioned into hot clips. Probably 400A but who remembers.
>
> He removed the old one confidently enough, grabbed the new one with
> rubber-handled pliers and gloves and...
>
>   Him: Have you ever played football?
>
>   Me: Actually, yes, I have, why?
>
>   Him: If something doesn't look right when I put this thing in just
>   tackle me clear of it as hard and as fast as you can.
>
>   Me: Um, ok.
>
> It all worked out fine and I wrote a memo that maybe Harvard could
> spring for a proper $500 breaker box?
>
> 
>
>
... and my "funny" story.

We used to live in San Jose. There was a large heat-wave, and much of SJC
lost power because of A/C load, etc. Anyway, my wife and I go and camp in
one of the office conference rooms for a few days because the office still
has power and A/C.
Eventually PG claims that power is back on our street, so we drive back
to San Jose and... no power. I flag down a passing PG truck and ask if
they know when it will *really* be back. Lineman says that it is. I say it
isn't. He says it is. I say it isn't.
He gets annoyed, opens up the pedestal box and sticks a meter in it, and
agrees that I have no power. He then sticks the meter across the 800A fuse,
and discovers that the fuse blew.
"Ah. I can fix that fer you..." he says, and goes to the back of the
truck... "Doh. I'm out of 800A fuses. Um er well, here is a 6,000A
fuse, that'll do..."

I briefly question the logic of this (presumably the lines in the ground
are sized somewhere around 800-1,200A), but he says that this'll do, and
he'll come back in the next few days to replace it. I lived there for
another 8 or so months, and it was never replaced, but, well,... not my
wires, so, um ¯\_(ツ)_/¯ I guess...

W

> --
> -Barry Shein
>
> Software Tool & Die| b...@theworld.com |
> http://www.TheWorld.com
> Purveyors to the Trade | Voice: +1 617-STD-WRLD   | 800-THE-WRLD
> The World: Since 1989  | A Public Information Utility | *oo*
>

-- 
The computing scientist’s main challenge is not to get confused by the
complexities of his own making.
  -- E. W. Dijkstra

Re: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-25 Thread Mel Beckman

Barry,

It’s really a problem. Several lineman are maimed or killed every year because 
of DIY ignorance. I’ve already provided one incident. You can easily find more.

It’s virtually impossible for lineman to protect against this risk while 
working. These guys aren’t idiots, they are highly trained professionals. They 
make sure power lines are de-energized from the grid before they touch them, 
but there comes a point where they have to put hands on in order to affect 
repairs. 

It’s while they are doing this hands-on work that some thoughtles homeowner 
decides to fire up his DIY wrongheaded generator, feeding 120 V backwards 
through a cascade of transformers to produce 12,000 or more volts. It takes 
only a few milliamps through the heart to kill someone. But often these 
accidents result in horrific third-degree burns.

We all know people, and we might even be people, who have home generators. I 
suspect many of these use direct attach rather than transfer switches. You 
could help teach them the right thing to do.

 -mel 

> On Aug 25, 2021, at 11:33 AM, b...@theworld.com wrote:
> 
> 
> Ok, I'll be the curmudgeon...
> 
> Is this really a problem in practice?
> 
> Most people I've known who worked around electrical mains etc assumed
> the worst at all times and it isn't all that difficult to protect
> against as one works.
> 
> I realize one can infinitely invoke "better safe than sorry!", "an
> ounce of prevention...!"
> 
> 
> 
> Except maybe that one guy at Harvard who came to replace what turned
> out to be a 100+ year old, home made, "breaker" which fed our machine
> room which was hidden in a narrow dark hallway winding around our
> machine room behind an unmarked metal, locked doorway. I had no idea
> it existed but we had no power so I called for help.
> 
> It was just a single copper bar about the size of a small candy bar
> tensioned into hot clips. Probably 400A but who remembers.
> 
> He removed the old one confidently enough, grabbed the new one with
> rubber-handled pliers and gloves and...
> 
>  Him: Have you ever played football?
> 
>  Me: Actually, yes, I have, why?
> 
>  Him: If something doesn't look right when I put this thing in just
>  tackle me clear of it as hard and as fast as you can.
> 
>  Me: Um, ok.
> 
> It all worked out fine and I wrote a memo that maybe Harvard could
> spring for a proper $500 breaker box?
> 
> 
> 
> -- 
>-Barry Shein
> 
> Software Tool & Die| b...@theworld.com | 
> http://www.TheWorld.com
> Purveyors to the Trade | Voice: +1 617-STD-WRLD   | 800-THE-WRLD
> The World: Since 1989  | A Public Information Utility | *oo*

Re: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-25 Thread Warren Kumari

On Wed, Aug 25, 2021 at 11:06 AM Jared Mauch  wrote:

>
>
> > On Aug 25, 2021, at 10:04 AM, Mark Tinka  wrote:
> >
> > You need to make these things fool-proof. We haven't traveled in over a
> year but the day we do, it's a recipe for disaster if the person that deals
> with this stuff is on the road when the power goes out back at home.
>
> This is why I personally spent the $$ on a proper standby generator with
> multiple ATS for the multiple panels.
>
>
Yah. I suspect that a fair bit of this depends on where you live. I have a
fairly rural house, and the power comes across the (Shenandoah) river, and
then down an overhead feed which branches off to 6 or 8 neighbors, before
running up the hill to a transformer on a pole near my house. We would lose
power around once every 2 or 3 months (trees, wind, snow, etc). We
installed a whole house generator (with transfer switch), and ... well,
actually, just after we did this the local power company did a bunch of
maintenance and now the supply is more stable, but still

This all reminds me that I need to go and do an oil change/maintenance on
the generator -- it sent me an alert the week before last that it has
reached its maintenance interval, but it's been a bit too hot to do this
yet...

W

- Jared



-- 
The computing scientist’s main challenge is not to get confused by the
complexities of his own making.
  -- E. W. Dijkstra

Re: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-25 Thread bzs



Ok, I'll be the curmudgeon...

Is this really a problem in practice?

Most people I've known who worked around electrical mains etc assumed
the worst at all times and it isn't all that difficult to protect
against as one works.

I realize one can infinitely invoke "better safe than sorry!", "an
ounce of prevention...!"



Except maybe that one guy at Harvard who came to replace what turned
out to be a 100+ year old, home made, "breaker" which fed our machine
room which was hidden in a narrow dark hallway winding around our
machine room behind an unmarked metal, locked doorway. I had no idea
it existed but we had no power so I called for help.

It was just a single copper bar about the size of a small candy bar
tensioned into hot clips. Probably 400A but who remembers.

He removed the old one confidently enough, grabbed the new one with
rubber-handled pliers and gloves and...

  Him: Have you ever played football?

  Me: Actually, yes, I have, why?

  Him: If something doesn't look right when I put this thing in just
  tackle me clear of it as hard and as fast as you can.

  Me: Um, ok.

It all worked out fine and I wrote a memo that maybe Harvard could
spring for a proper $500 breaker box?



-- 
-Barry Shein

Software Tool & Die| b...@theworld.com | http://www.TheWorld.com
Purveyors to the Trade | Voice: +1 617-STD-WRLD   | 800-THE-WRLD
The World: Since 1989  | A Public Information Utility | *oo*

Re: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-25 Thread Michael Thomas




On 8/25/21 11:11 AM, Jay Hennigan wrote:


The question that Ethan raised makes sense, however. If power to 
several blocks is out and I connect my little 2KW Honda to my house 
wiring without a transfer switch, because transformers work in both 
directions my generator will see the load of the whole neighborhood. 
This will immediately and severely overload the generator and at best 
cause it to stall out or trip its output breaker, at worst to fail 
catastrophically.


I know that a nearby house burned down and was blamed on back feeding 
the grid. I assume that it failed catastrophically. Bad idea all around.


Mike

Re: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-25 Thread Lady Benjamin Cannon of Glencoe, ASCE

So the issue here is even a small 120vac current becomes a very fatal event at 
7.2 or 11 or 14.4kV.  It’s a safety issue for linepersons doing emergency 
restoration work.

Ms. Lady Benjamin PD Cannon of Glencoe, ASCE
6x7 Networks & 6x7 Telecom, LLC 
CEO 
l...@6by7.net
"The only fully end-to-end encrypted global telecommunications company in the 
world.”

FCC License KJ6FJJ

Sent from my iPhone via RFC1149.

> On Aug 25, 2021, at 7:24 AM, Ethan O'Toole  wrote:
> 
> 
>> 
>>> How would this not load the generator or inverter into oblivion?
>> Not sure I understand your question. Say again, please.
> 
> If you hook 100KW of neighbors up to your 5KW/20% THD garden generator it 
> would probably trip the breaker, or stall.
> 
> I suppose it could be an issue if it was a single house on a branch where the 
> break being serviced was just that branch (rural customers.)
> 
> Was just curious why it wouldn't overload the generator trying to power all 
> the neighbors houses if connected to the grid.
> 
>- Ethan
>

Re: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-25 Thread Jay Hennigan


On 8/25/21 10:25, Mel Beckman wrote:

Jay,

No, because transformers work in both directions :)


I think you mean, "Yes, because transformers work in both directions." 
First of all, I absolutely agree that no one should attempt to energize 
their home wiring with a standby generator unless there is a proper 
transfer switch in place. I very much understand the safety concerns.


The question that Ethan raised makes sense, however. If power to several 
blocks is out and I connect my little 2KW Honda to my house wiring 
without a transfer switch, because transformers work in both directions 
my generator will see the load of the whole neighborhood. This will 
immediately and severely overload the generator and at best cause it to 
stall out or trip its output breaker, at worst to fail catastrophically.


In the very rare case that the outage is at the fuse on the pole pig 
feeding just my house or that of me and one or two neighbors, then 
indeed the generator may continue to run and that transformer will have 
distribution voltage of 4KV or so on the utility side, a very dangerous 
condition. That's a pretty unusual situation, however. Typical power 
outages are substantially more widespread. My little generator would be 
looking at the load of the entire outage area reflected through the 
(bidirectional as you note) transformers. The load of half the town 
will, as Ethan speculated, completely overwhelm any practical 
residential standby generator to the point that it stops producing power 
either by failure or by tripping its breaker.


Even if the generator were massive and survived, its branch circuit 
breaker or the house main would trip long before sufficient power to 
feed a large area was able to flow back into the utility's wiring.


Yes, connecting a generator without a transfer switch is a horrible idea 
and likely to get someone killed, agreed.*  However, as the vast 
majority of power failures involve more than a single residence, the 
generator will fail to produce power immediately anyway due to looking 
at essentially a dead short.


* Every time I've seen utility workers working on lines that are assumed 
to be dead, the first thing they do is clamp them to ground to be 
certain. When the lines are assumed to be live, massive insulation 
sleeves, heavy gloves, insulated booms and the like are used.

--
Jay Hennigan - j...@west.net
Network Engineering - CCIE #7880
503 897-8550 - WB6RDV

Re: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-25 Thread Matt Erculiani

In theory, Jay is correct, but assuming that theory will always work in
practice is, in this case, how linemen end up dead. We're all well aware of
never assuming theory = practice, but admittedly the stakes tend to be a
little lower in our world.

Ensuring that a generator physically cannot backfeed is just one layer of
protection against the already very high risk of the job of a lineman. Then
there is, of course, checking for the presence of voltage before starting
work, but it's possible for a generator to start AFTER this check.

Another layer of protection is grounding all conductors prior to beginning
work, so that if power does come back (via the grid or a backfeed) A: The
lineman and bucket is not the best path to ground and B: The source is
tripped.

Reading through that forum post, it sounds like that particular contractor
had a reputation for lacking proper safety precautions, so one or more
safety layers may have been removed, making the risk/impact of any single
mistake much greater than it should be.

-Matt

On Wed, Aug 25, 2021 at 11:25 AM Mel Beckman  wrote:

> Jay,
>
> No, because transformers work in both directions :)
>
> Plus, to the previous commenter that talked about “suicide cords”:
> they’’re more correctly termed “homicide  cords”:
>
> “ The lineman killed yesterday was working for Pike Electric and picked up
> a line that was connected to someones house that hooked up a generator and
> did not disconnect from the distribution system. The linemans name was
> Ronnie Adams, age unknown. He had two children and a wife. As far as I know
> he was from Louisiana. They are trying to set up a fund for his family, but
> nothing I have heard of yet. I will let yall know more as I hear of it. I
> wish they would really teach folks the proper connection of generators,
> this was a really tragic and preventable accident. Stay Safe and think
> about it before you do it.”
>
> https://powerlineman.com/lforum/showthread.php?711-Storm-Death
>
>  -mel
>
> On Aug 25, 2021, at 10:12 AM, Jay Hennigan  wrote:
>
> On 8/25/21 07:04, Mark Tinka wrote:
>
> On 8/25/21 15:59, Ethan O'Toole wrote:
>
>
> How would this not load the generator or inverter into oblivion?
>
> Not sure I understand your question. Say again, please.
>
>
> If you fail to isolate your generator from the incoming utility feed so
> that you're back-feeding the utility and the power is out for your
> neighborhood or the whole city, would not the load of trying to light up
> the whole town completely overwhelm your little generator to the point that
> it fails, stalls, or trips its own output breaker?
>
> --
> Jay Hennigan - j...@west.net
> Network Engineering - CCIE #7880
> 503 897-8550 - WB6RDV
>
>

-- 
Matt Erculiani
ERCUL-ARIN

Re: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-25 Thread Mel Beckman

Jay,

No, because transformers work in both directions :)

Plus, to the previous commenter that talked about “suicide cords”: they’’re 
more correctly termed “homicide  cords”:

“ The lineman killed yesterday was working for Pike Electric and picked up a 
line that was connected to someones house that hooked up a generator and did 
not disconnect from the distribution system. The linemans name was Ronnie 
Adams, age unknown. He had two children and a wife. As far as I know he was 
from Louisiana. They are trying to set up a fund for his family, but nothing I 
have heard of yet. I will let yall know more as I hear of it. I wish they would 
really teach folks the proper connection of generators, this was a really 
tragic and preventable accident. Stay Safe and think about it before you do it.”

https://powerlineman.com/lforum/showthread.php?711-Storm-Death

 -mel

On Aug 25, 2021, at 10:12 AM, Jay Hennigan  wrote:

On 8/25/21 07:04, Mark Tinka wrote:
On 8/25/21 15:59, Ethan O'Toole wrote:

How would this not load the generator or inverter into oblivion?
Not sure I understand your question. Say again, please.

If you fail to isolate your generator from the incoming utility feed so that 
you're back-feeding the utility and the power is out for your neighborhood or 
the whole city, would not the load of trying to light up the whole town 
completely overwhelm your little generator to the point that it fails, stalls, 
or trips its own output breaker?

--
Jay Hennigan - j...@west.net
Network Engineering - CCIE #7880
503 897-8550 - WB6RDV

Re: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-25 Thread Sabri Berisha

- On Aug 25, 2021, at 7:04 AM, Mark Tinka mark@tinka.africa wrote:

Hello Mark,

> At the home, you typically have someone that is responsible for knowing
> what to do in case of an outage, and switching over to self-generation.
> If that person is not there, or has passed out from too many bottles of
> wine that evening, someone else might think it's just a matter of
> starting the generator, unwinding a suicide cord and plugging it into
> the wall - totally forgetting about the main breaker.

At my home, I use this: https://www.amazon.com/gp/product/B00CONE4MG

The interlock kit is installed in such a way that either the main or 
the generator circuit breaker is closed. If the main is on, you can't
switch to generator power, and vice versa (see the pictures on the
listing, mine is installed the exact same way).

Thanks,

Sabri

Re: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-25 Thread Jay Hennigan


On 8/25/21 07:04, Mark Tinka wrote:



On 8/25/21 15:59, Ethan O'Toole wrote:



How would this not load the generator or inverter into oblivion?


Not sure I understand your question. Say again, please.


If you fail to isolate your generator from the incoming utility feed so 
that you're back-feeding the utility and the power is out for your 
neighborhood or the whole city, would not the load of trying to light up 
the whole town completely overwhelm your little generator to the point 
that it fails, stalls, or trips its own output breaker?


--
Jay Hennigan - j...@west.net
Network Engineering - CCIE #7880
503 897-8550 - WB6RDV

Re: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-25 Thread Dave

Back feed is a significant problem but bringing a generator that is not 
synchronized to the grid can have dramatic results, typically only once

Dave

> On Aug 25, 2021, at 11:11 AM, Mark Tinka  wrote:
> 
> 
> 
> On 8/25/21 16:59, Jared Mauch wrote:
> 
>> This is why I personally spent the $$ on a proper standby generator with 
>> multiple ATS for the multiple panels.
> 
> Same here.
> 
> Massively painful, which led to some boring moments testing, testing and more 
> testing. But after 5 months with electricians, electrical certifiers, battery 
> vendors and inverter vendors (and a little voltage/amp sensor to capture slow 
> voltage grid brownouts that kept tripping my battery), it's been solid for 
> nearly a year. And looking good.
> 
> I can now travel and not worry about the Mrs. waking me up from my sleep, on 
> the far side of the world :-).
> 
> Mark.

Re: Reminder: Never connect a generator to home wiring without transfer switch





On 8/25/21 16:59, Jared Mauch wrote:


This is why I personally spent the $$ on a proper standby generator with 
multiple ATS for the multiple panels.


Same here.

Massively painful, which led to some boring moments testing, testing and 
more testing. But after 5 months with electricians, electrical 
certifiers, battery vendors and inverter vendors (and a little 
voltage/amp sensor to capture slow voltage grid brownouts that kept 
tripping my battery), it's been solid for nearly a year. And looking good.


I can now travel and not worry about the Mrs. waking me up from my 
sleep, on the far side of the world :-).


Mark.

Re: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-25 Thread Jared Mauch




> On Aug 25, 2021, at 10:04 AM, Mark Tinka  wrote:
> 
> You need to make these things fool-proof. We haven't traveled in over a year 
> but the day we do, it's a recipe for disaster if the person that deals with 
> this stuff is on the road when the power goes out back at home.

This is why I personally spent the $$ on a proper standby generator with 
multiple ATS for the multiple panels.

- Jared

Re: Reminder: Never connect a generator to home wiring without transfer switch





On 8/25/21 16:24, Ethan O'Toole wrote:



If you hook 100KW of neighbors up to your 5KW/20% THD garden generator 
it would probably trip the breaker, or stall.


Assuming that you don't want to deliberately simulate a utility grid on 
the same transformer as your neighbors, the bad news is that line 
workers could be injured by your back-feeding. Not so likely for your 
neighbors because they wouldn't be touching the lines, but yeah, not 
great for line workers actually working on them.


At any rate, you will trip any generator once you overload it. Worst 
case, you'll burn out its electrical components.





I suppose it could be an issue if it was a single house on a branch 
where the break being serviced was just that branch (rural customers.)


Typical assumption, regardless of it's urban or rural, as each house 
would have its own main breaker anyway - both at the customer panel, as 
well as at the utility source point (last one may vary by country).





Was just curious why it wouldn't overload the generator trying to 
power all the neighbors houses if connected to the grid.


If you did not isolate your self-generation equipment from the grid, 
then you may very well become a provider for your neighbors all hooked 
on to the same distribution wiring, or even on the same transformer.


It would likely never work in any meaningful way, and you increase your 
chances of starting a fire or breaking things irreparably.


AC-coupled grid-tied solar inverters automatically stop making PV power 
once the grid disappears, to avoid this very problem, if you do not have 
a local battery to substitute. This is defined under UL 1741 that all 
major PV inverter OEM's follow. There have been some changes defined 
under "California Rule 21 Tariff" that ease UL 1741 somewhat, to avoid 
PV inverters from disconnecting from the grid during an outage in order 
maintain grid stability, i.e., when a grid provider is accepting 
significant amounts of feed-in from private or commercial 
self-generation customers, a sudden disconnect of all that capacity 
during a main grid outage could make for a very unstable grid due to 
massive and sudden variations in voltage and frequency.


I'm not yet sure of any other places besides California that implemented 
this requirement against PV inverter OEM's. I haven't tracked it since 
2017. I know that here in South Africa, UL 1741 is still the main and 
only requirement.


A grid-tied battery inverter will automatically disconnect from the grid 
when it disappears, so it has no chance of transferring PV or battery 
energy on to the grid network.


Generators are not usually that intelligent. Some manual switching 
required to avoid grid back-feed, which was Sean's initial point. If 
done well, the generator would have an ATS (automatic transfer switch, 
either integrated or an add-on) to take care of all of this. In the 
absence of that (due to cost management or a lack of a thorough job), a 
manual changeover is highly recommended.


Mark.

Re: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-25 Thread Ethan O'Toole


 How would this not load the generator or inverter into oblivion?

Not sure I understand your question. Say again, please.


If you hook 100KW of neighbors up to your 5KW/20% THD garden generator it 
would probably trip the breaker, or stall.


I suppose it could be an issue if it was a single house on a branch where 
the break being serviced was just that branch (rural customers.)


Was just curious why it wouldn't overload the generator trying to power 
all the neighbors houses if connected to the grid.


- Ethan

Re: Reminder: Never connect a generator to home wiring without transfer switch





On 8/25/21 15:59, Ethan O'Toole wrote:



How would this not load the generator or inverter into oblivion?


Not sure I understand your question. Say again, please.




(Just curious, I know people who use a suicide cord usually turn off 
the main breaker.)


At the home, you typically have someone that is responsible for knowing 
what to do in case of an outage, and switching over to self-generation. 
If that person is not there, or has passed out from too many bottles of 
wine that evening, someone else might think it's just a matter of 
starting the generator, unwinding a suicide cord and plugging it into 
the wall - totally forgetting about the main breaker.


You need to make these things fool-proof. We haven't traveled in over a 
year but the day we do, it's a recipe for disaster if the person that 
deals with this stuff is on the road when the power goes out back at home.


Mark.

Re: Reminder: Never connect a generator to home wiring without transfer switch

2021-08-25 Thread Ethan O'Toole


 Back feeding electric power into the utility lines is dangerous for the
 repair crews working on utility lines.

Same advice applies to solar or stationery storage inverters. Typically,
these are automated enough to disconnect from the grid after an outage, 

if
you don't have a local battery; or the battery inverter will isolate 

away


How would this not load the generator or inverter into oblivion?

(Just curious, I know people who use a suicide cord usually turn 
off the main breaker.)


- Ethan

Re: Reminder: Never connect a generator to home wiring without transfer switch